Couple of questions

To answer your first question, modern top-quality GPUs are fast enough that they can handle lower resolutions by themselves. Look at some benchmarks, but adding another one in SLI (or Crossfire, if ATI) just doesn't make a difference.
On the second question, others can answer better than I can, but at this point I would not worry about it. By the time there are titles where DX10.1 matters compared to DX10, there will probably be yet another generation of GPUs out there (maybe two or three).
On your third question, the games don't speed up any appreciable amount when the CPU is overclocked because the bottleneck is the GPU, not the CPU. If the same game is run at lower graphics settings, there will be a more visible difference, but at high settings there may be none at all. In that case, you would oc your CPU because:
1. You want other things to be faster, like rendering tasks, background processes, etc.
2. You want to reach the point where the GPU has become the bottleneck (i.e. you're getting the most you can out of that CPU)
3. You just feel like it, as a technical challenge. How high can you go, or just how erect is that e-phallus?

Q1: you don't sli at lower resolution because you can buy a slightly more expensive card that can run -most- games at full detail at that resolution, no reason to buy 2 200$ cards when 1 300$ can do the job with no sli scaling issues, less power and space used.
Q2: dx10.1 is only now being used, assasin's creed had it but removed it in a patch. EA and atari has games with dx10.1 in the pipeline. An 8800gt would be a better buy now, but for slightly more you can get a 9800gtx or a hd4850.
Q3: clock speeds only make a difference if the cpu is slow, a E2200 or amd 5000+ would need a higher clock to make up for the lower cache they have against cpu's like E8500 and Q6600. But as you can see clock speed is still a bit significant but games prefer a bigger cache. A q6600 @ 3.0ghz would be enough for most games now.
Edit: damn, got beat again, rather listen to jtt xD

SLI/CF in the past have very big scale problem but now in every game there is no problem now since after the release of the 3870X2 and 9800GX2. as the 2 big company really opened up the market for dual GPU so game developers needs to optimise for SLI/CF system. when at lower resolutions SLI wont bring you noticable increase as most powerful card run it at 60fps+ even if add another card bring you 100% scale(always impossible) of 120fps+ can you SEE the extra 60FPS? the answer is no. it will just stay fluid as it is.

also multi GPU have another downside is that you will need a motherboard that support 2 card and a power supply thats powerful enough to run 2 card. also SLI/CF is very CPU limited as the looks of today, as those card setup is data hungry so the CPU need to be fast enough to keep up.

DX10.1 will never make it as DX10 still got a lot to optimise before the game developers can really move on. its been said that the graphics world will jump from DX10 to DX11. so the DX10.1 is not a real world benefit at the moment. Physics in game is the next thing in game rather then DX10.1.

from the 1st paragraph it brings to your CPU OC question. the higher the speed the better, this is because the intel system is communicate through the FSB which will be higher if you overclock it. it will allow greater memory bandwidth. you will see ALOT of frame rate difference in a SLI/CF setup when the Q6600 ius running at 2.4Ghz compare to 3.2Ghz. also a system is not just for game, others will use it in photo editing, video editing or even some heavy data calculation they are all very CPU dependant and memory dependant. if a game or a application is optimised for multi thread rather then dual thread you will see alot of difference in performance when compare to a quad core CPU. the time it takes to do the same task will be helved.

for your card buying. if you already got a SLI mobo get the 8800GTS G92 512 SLI, as those card is very good performer at its new low price. but if you have a intel p35/35 X38/48 get the HD4850 CF setup. but bare in mind that the HD4xxx card is very loud at the moment and very very hot. they loaded at 80-90C+

OK, let me clarify something, i am NOT goin to do ANY photo or video editing...i will be gaming and web surfing lol... umm yeah i'm not really too keen on sli actually....but with a single 8800GT and a E8400 or Q6600, which would be the better mobo to overclock and provide stability: X38, 750i or something else? thanx for the dx 10.1 responses, that cleared it up lol. But i thought that GPU's bottlenecked pretty much every cpu! i see threads saying the 8800GT will bottleneck even an OC'd Q6600! please clarify?

thanks for your reponses anyhow guys, it was a help. Keep em comin'!

and btw i am not completely noob lol...i know that two gpu's does not = double the performance.... i do my research!  

even tho my profile says newbie....only means im new to tom's forums lol  

hey guys, just slightly off topic here, but concerning the application of thermal greases/pastes, arctic silver says you should apply the grease to the CPU heatspreader, while this article here: http://benchmarkreviews.com/index.php?option=com_conten..., Assumes that it is applied to the cooler!! can anyone confirm? please guys i'm a little confused here.

it doesnt really matter where you apply thermal paste. when you put the cooler on all the extra thermal paste is gonna get sqeeze out to the side. i usually spread the thermal paste to the ihs.

i dont know where you done your research, a OCed Q6600 will not bottleneck a 8800GT. you should read a article here it tested a E2180@3Ghz will not be bottlenecking the system. and it also said a core 2 dual processor above 2.8Ghz can extract all the performance out of all the modern graphics cards.

it really depend how long you want to keep your PC. because E8xxx can OC to 4Ghz+ no problem. where as the Q6600 will be max out at 3.6-3.8Ghz with the best aircooler at a moderate noise level.

when games and application become more the dual threaded, the Q6600@2.4Ghz will whoop any dual core processor at 4Ghz. but this has been argue and argue again. its your call to pick current game king or future "proof" long run.

from the current situation i will pick the X38/48 over those Nvidia chipset.

err gill....the purpose of that article was to find which way to spread the paste so it DOES spread to all the sides....if you had read the article you would have seen the pictures showing different methods NOT REACHING THE SIDES!! i agree spreading it to the ihs...

OK, well then, what CPU would be like sorta 1:1 with a 8800GT then? like no bottlenecking either way? or a GPU thats 1:1 with an E8400 (yes i have made my choice for that kind of...) and yeah i want to keep my computer for a few years until the hardware is not up to scratch for some game that i bought... in which case i will OC it till it explodes, or plays the game! i've made my choice with a xigmatek HDT 120mm something ( i cant be bothered memorising the product code)....as its significantly cheaper than an OCZ Vendetta 2, which would be my choice if not for the price...

Does anyone actually know of developers planning to make future games quad threaded? i mean, mainstream users of games would BUY the whole computer off Dell for example, not build one, and it's hard to find a quad core in dell's line up under $2000...

And i got a lotta research to do with the motherboard....thought i had made a choice but hmmm.... in any case it will all come down to what my local supplier has in stock! i will NOT buy any computer parts off a company in the US unless it has free shipping!! (i live in australia - expensive for shipping....   )

anyhow thanks for your replies.

V3NOM WAZ HERE  

and err... what will overlock a E8400 better - intel P45 or nvidia 750i (evga's redone ftw edition....)? also, does EPP or XMP actually offer any benefits to RAM? bit confusing...

P45 will be better much better.
and use any 1066 ram will be best, as both E8400 and P45 is very high OCer so you will need some good ram to keep up with it.

I would go with the P45 chipset as the 750i is crap for overclocking compared to the P45.

i have seen that article before. but have you think if the same amount of thermal paste is being put on the IHS, do you think the result will differ? i havent experiment it myself but its pretty logical. if the same tiny amout used in the dab test being apply in the "||" style. do you think there will be enough thermal paste to spread out to all of the IHS? i dont think so.

Well, according to arctic silver (about AS5)http://www.arcticsilver.com/pdf/appinstruct/as5/ins_as5... (dual core) and http://www.arcticsilver.com/pdf/appinstruct/as5/ins_as5... (quad core), yes! they say a single line between the two (or four) cores of the cpu, so that the heat will spread out evenly. I personally do not think it matters if it spreads to all the edges, so long as it is covering the cores!  

Also, i will only need 1066 RAM if my FSB is 533 correct? i doubt i can, or would be willing, to go that far...

yes you are "right" as 533x2=1066.good maths!lol

yeah lol iluvgill....and i didnt even use the windows calculator!! anyhow i think i will just get some low timing 800MHz like corsair twinx whatever....as i will not be going past 400 FSB....i do want to keep my comp running for a couple of years lol! im not that rich to replace it every year...

but over 400FSB i think it will still run over 2 years. thats what i think anyway.

meh, idk..... i think i will OC to play the latest game if necessary adn then if i get a game that needs higher, i OC more? dunno if that would work....but surely that would extend the lifespan of it instead of OC'ing when its not necessary.... i really dont care about bragging rights LOL.