Hi There,
 
Its time to rebuild my PC, after couple of weeks research, I came up with following spec. This system will mainly for gaming and home use with a budget of 1500USD.
 
1) Intel Core 2 Quad Q6600 Kentsfield 2.4GHz 2 x 4MB L2 Cache
2) ARCTIC COOLING Freezer 7 Pro 92mm CPU Cooler
3) OCZ Reaper HPC Edition 4GB(2 x 2GB) DDR2 800  
4) GIGABYTE GA-P35-DS3L LGA 775 Intel P35 ATX
5) MSI NX8800GT 512M OC GeForce 8800GT 512MB GDDR3 (Core Clock: 660Mhz)
6) Seagate Barracuda 500GB 3Gbps 7,200RPM
7) Antec 900 Gaming Cabinet
8) Cooler Master 600W SMPS
9) Dell 22” WS TFT (1680 x 1050 Native)
 
I understood from several reading that we can OC Q6600 to 3.6 on GIGABYTE P35-DS3L and OCZ Reaper DDR2 800 with Freezer 7 Pro. Is this really safe with the above spec?  
 
Is 600W power supply enough for the above spec with OC? I have not plan for SLi/Crossfire.
 
As I have no plans for SLi, will 8800GT 512M OC capable for decent gaming? Mainly FSX, COD4, BF2, CMR DiRT, etc. at 1680 x 1050 with extreme possible graphics. Or should I consider the nForce motherboards for SLi enhancements in the future?
 
Also from the readings I found that DDR2-800 would be the best pick for up to Q6600 3.6Ghz. Am I correct?
 
Will I be gaining any performance advantages in the above spec, if I replace the 7,200RPM (3Gbps) HDD with 10,000RPM (1.5Gbps)?
 
I know this system is not future proof. From several readings I understood that investing on DDR3 is not worth at the moment because none of the existing processors are capable of using DDR3 bandwidth and the latencies are very high compared to DDR2.
 
Any suggestions/inputs are greatly appreciated.
 
Many thanks

Are you in the US?  
If you are, I would change to the power supply to this;
http://www.buy.com/prod/Corsair-VX [...] 52646.html
This cooler;
http://www.mwave.com/mwave/skusear [...] ia=BA24691

If you're gonna OC it, I think Gigabyte X38 DS4 or higher or ASUS X38 series will be better, because they have a better chipset cooling system and including SLI and RAID functions. nVidia and Intel chipset are not that different in performance, just choose as you like (nVidia n750i). But honestly I would go for X38.
 
Corsair VX550W is indeed better as coolermaster, but 550W is not going to  be enough on SLI configuration. So think over it carefully  before you buy a PSU: Are you gonna SLI now or someday?  
 
I say finger off from SLI/crossfire configuration. Such a configuration is juat a waste of power consumption and money. You're not gonna get twice altough you have paid twice. But for some people this is not a problem. So it's up to you.  
 
And about the cpu heatsink, I think artic freezer pro 7 just won't make it that high (3,6GHz) try to consider these :
1. Zalman cnps9700 (I use this right now, result : good looking, cool, and silent)
2. Scythe ninja cu edition  
 
WD 10k rpm is not that good, go for Seagate 7200.11 500GB 32MB. RAID 2x this Seagate 7200.11 if you want.
 
If you looking fo better video gaming performance, just use 19'' monitor not a 22''.
 
DDR3 is the future but, in the moment,way too expensive. Just stick to DDR2 for now. Unless if that amount of money is not a problem to you.

I’m not in the US but panning to get the items from Newegg.com and ship through my friends.  
 
X38 boards starts at $200 where P35 available for $90, is it really worth the difference? What could be the best OC settings I can get with P35? Also GA-DQ6 has PCIE 2.0, should I consider that for better gaming performance?
 
I agree with you and not planning to SLi, its not worth the cost. With no SLi in mind, do we need to consider nForce boards?
 
Should I go for 550W or 600W power supply for above spec without SLi?
 
I do agree with Zalman 9700, red good reviews as well. I initially planned for it but then switched to Freezer 7 because its $20 less in cost. I think its worth considering Zalman 9700.
 
What gaming difference could a 19” and 22” cause with 8800GT? I thought I can enjoy the larger display.

Totally agree with both of these suggestions. The CM PSU that you selected isn't rated very well, see my Tier link in my signature to see what PSU you should get. The Corsair brands are made well and have a 5 yr. warranty too. If you have any doubts on the CPU HSF, read this review below on the Xigmatech HSF and others.
 
Frosty’s Review of Xigmatech HDT-S1283 CPU Cooler
http://www.frostytech.com/articlev [...] 233&page=1
 
I'd also try and get a 8800gts (g92) if you can fit it into the budget. It's about 10% faster and will last you a bit longer than the 8800gt. The 8800gts is a double slotted solution and will run a bit cooler than the 8800gt, which is only a single slot cooling solution (in general).

Xigmatek HDT-S1283 looks interesting, available at $37 from Newegg.  
 
EVGA 8800GTS (G92) 512MB availeble for $260 ($40 more than GT). Is it worth the difference? Sorry I'm not questioning your advice, just clarifying the doubts.
 
Thanks for the advices.

This is a general question to everyone but for a gaming machine why wouldn't you go SLI/Crossfire.  I'd think that a E2160 + 2 8800gt(s) would run games faster than a Q6600 + 1 8800GT.  Plus you can add the 8800gt later when preformance dictates whereas the processor is a sunk cost.  A friend of mine just got a 5000+ with a 3870 with plans on getting an 3870x2 or 4870x2 if that works later.  I bet one he upgrades to crossfire that machine would run circles around this one and it only cost him about $1,000 + $400 for the upgrade when he needs it.

If you add in the shipping from Newegg, you'll see that it's more like $44 shipped. The Mwave deal that Chuckm posted is much better and you still get the same thing.  The 8800gts is going for $230 after $30 MIR, so I'd get that over the 8800gt, if I could afford it. The main reasons for getting the 8800gts over the 8800gt, I've already stated (runs cooler and is 10% faster or more). You can decide what you want to do, but that is the direction that I would go. Make sure you get a better PSU too, like the one Chuckm linked.

+ the 8800 gts a3 version is also 230$ and comes with crysis if you dont have it. thats 45$ saved

X38 boards starts at $200 where P35 available for $90, is it really worth the difference? What could be the best OC settings I can get with P35? Also GA-DQ6 has PCIE 2.0, should I consider that for better gaming performance?
X38 is new and P5E X38 has a HD audio card. the rest is about the same just like P35. About P35 taht cost only about $90, that is the DS3 series, if you look at better cooled mobos and they are not very different in price with x38.  
If you are gonna OC, I suggest that you look for a better mobos but naturally more expensive, with better cooling system. That is just about all.
But if you ask me than yup ds3 should be enough but if you are going to OC your system, perhaps a better cooled mobo will have a longer lifetime. P5EX38 and Gigabyte X38-DS5 have a decent price.
'bout PCIex 2.0, this depends also on your vga card.
 , the question is : is your vga card a PCIex 2.0? when not then it has no difference at all.
 
I agree with you and not planning to SLi, its not worth the cost. With no SLi in mind, do we need to consider nForce boards?
Without SLI, there is nothing too different between nForce and P35 or X38. You will use only 1 VGA anyway. But my friends told me that P35 and X38 can OC better than 750i.
 
Should I go for 550W or 600W power supply for above spec without SLi?
550W should do just find but please check at http://web.aanet.com.au/SnooP/psucalc.php .  
 
I do agree with Zalman 9700, red good reviews as well. I initially planned for it but then switched to Freezer 7 because its $20 less in cost. I think its worth considering Zalman 9700.
Well I know artic freezer is good (still not as good as 9700 though) and cheap but **** loud compared to cnps9700! and 9700 looks better hehehehehe....
 
What gaming difference could a 19” and 22” cause with 8800GT? I thought I can enjoy the larger display.
Larger screen requires larger performance from your VGA-Cards, just stick with 19'' it is enough.  
Have you take a look at the ATI X3850 or X3870? or the new nVidia 9600 and 9800 series? They have the about same performance but less power, this can reduce your monthly electrical bill.

First of all, let me thank you all for posting your opinion and helping out to choose the best gaming option available.
 
After reading the above posts, I’m charged up and looking forward for Crossfire or SLi. Now, the question is which one to go for, SLi or Crossfire? I’m aware that Crossfire solutions will be cheaper than SLi’s and also I have red few reviews on 8800GTS beat X3870.
 
Crossfire Option:
------------------------
Intel Core 2 Quad Q6600    $255
ASUS P5E X38 [1600FSB]    $225
DIAMOND Viper HD 3870 512MB GDDR4 PCIEs 2.0   $200
      -------
Total      $680
 
 
SLi Option:
-----------------
Intel Core 2 Quad Q6600    $255
EVGA NF78-A1 780i SLI [1333FSB]    $260  
EVGA A3 8800GTS (G92) 512MB GDDR3 PCIE 2.0   $260
      -------
Total      $775
 
 
If we are voting for a Crossfire option, do we need to consider Phenom 9600 instead of Q6600? AMD will have better performance on Crossfire than Intel? Q6600 beat P9600 in all the reviews with significant margin. How about P9600 over clocking?  
 
AMD Option:
-----------------
AMD Phenom 9600 Agena 2.3GHz    $230
GIGABYTE MA790FX-DS5     $180
DIAMOND Viper HD 3870 512MB GDDR4 PCIEs 2.0  $200
      -------
Total      $610
 
 
And of course, OCZ GameXStream 600W PS [Tier 2] $110
 
 
Thank you.

Crossfire Option:
------------------------
Intel Core 2 Quad Q6600    $255
ASUS P5E X38 [1600FSB]    $225
2x HIS Hightech TURBO HD 3870 512MB GDDR4 PCIEs 2.0   $440
      -------
Total      $920 + around 650W PSU (yup! X3870  demands less power)
 
 
SLi Option:
-----------------
Intel Core 2 Quad Q6600    $255
ASUS P5N-T deluxe 780i SLI [1333FSB]    $250  
2x EVGA A3 8800GTS (G92) 512MB GDDR3 PCIE 2.0   $520
      -------
Total      $1025 + around 750W PSU
 
If you're goin' for 2xVGA-card, then don't forget the correct PSU.  
 
Both of these options are good.  
I prefer to choose your crossfire option due to budget reason.  
But if you're gonna use it only for gaming that Q6600 won't be that much of an effect. You can also consider E8400 or Xeon E3110 for cheaper, faster but only 2 core, overclockable but less power consumption.  
 
Forget the old Phenom9600 until the one with the bug revision is out there on the market, which is perhaps in a short time in the future.

Thanks for the input; I still like to stick with Q6600 as future is multi threaded.  
 
Almost all the reviews rated 8800GTS (G92) well over HD3870. I will be using a resolution of 1680x1050 or 1600x1200. For this resolution, what could be best pick? I prefer the best performance at around GTS budget.

OK...lets start to order those stuffs!