I have a new build in mind...I am finally jumping on the Core 2 bandwagon...
 
How will this build overclock?
 
 
Intel Core 2 Quad Q6600 processor
 
Gigabyte P35-DS3L Intel P35 chipset motherboard
 
2x1gb kit G. Skill DDR2 800 memory (5-5-5-15 CL)
 
Cooler Master Centurion 5 case
 
OCZ StealthXStream 500w PSU
 
Western Digital 160 gb SATA II hdd

That should overclock fine, but what video card are putting in there? Wouldn't want to push the OCZ 500W PSU too much with a Quad OC and high end card.  
 
Anyway, 3.0Ghz should be really easy for you. All you'll need to do is literally change the FSB in bios from 226 (1066/4) to 333 (1333/4) since the Q6600 runs at 1066 stock and your motherboard is 1333.  
 
Beyond that, you could theoretically hit 3.6Ghz with DDR2 800mhz though not many chips can do that on air cooling, and definately not with the heatsink that comes with the Q6600. Personally, I would get a Tuniq Tower 120 or an Ultra-120 (fan sold seperately though with the Ultra) if you plan on OCing beyond 3Ghz.

400x8 is possible at 1.25v with a very nice air cooler, but its still going to run quite warm, one of swiftech's 120 or 220 compact water cooling units (very simple to install) makes for easy stability.  

Pushing the q6600 over 3ghz can/does indeed require water cooling.  
 
 
3.7ghz??
http://www.tankguys.com/product_re [...] 625f349ba5

why W/C with a 3.2ghz OC? Theres no point. W/C only for higher 3.6+ overclocks (if you find you need that)
 
Running 3.3ghz at the moment 1.24 idles at 38 load 60. (Tuniq tower air cooling)

note the "can/does." The ambient temperature comes into play. Also,  Identical chips have heat variance at the same clock speed.  
 
In reality, a tuniq tower should take you to 3.2 or 3.3 with no problems.

 
Don't be stupid.  A GO/x3210/3220 will easily due 3.4-3.6ghz without exceeding voltage specs with a decent after market cooler.  B3 will do 3.2-3.4.

Alright.
 
For a 3-3.2 overclock, would an Arctic Cooling Freezer 7 Pro be sufficient?
 
And the video card will more than likely be a 9600 GT.

Also, what would be the exact voltage I would want for 400x8?
 
That would give me a 1600mhz FSB, correct?

Well that will partially depend on your ambient/room temperatures and how good the air flow is in your case, but yes you MAY be able to get 3.2 with that cooler.. although I wouldn't recommend it. It's a great value cooler and definately better than the stock one, but the quads just get very hot very fast. It's up to you, I'm sure there are many people who are using it but I would REALLY recommend spending the extra ~$25 and getting the Tuniq Tower 120. Especially since I don't think that case has many fans to move air (maybe check out the Coolermaster 690, I think it's around the same price).
 
EDIT: Kind of, but every CPU is different so you'll have to play around with it yourself. But you definately want to look into water cooling if you're thinking about pushing the full 400mhz O_o (hot hot hot!)  There's some good threads on the forums at xtremesystems.org about what people get for their voltage settings, it might be a good place to start but again every chip is different. If this is your first overclock, get it running smoothly at 3Ghz which should be very easy (no voltage changes) but then go up very slowly because quads will eat up a lot of power and general a lot of heat fast, don't just shoot for 3.2+ right off the bat

Why the raptor?  Yes they're nice, but I would find having more space far more useful than the speed.  Plus, for most day-to-day uses a modern 7200RPM drive can usually keep up.
 
-mcg

 
Just drop a 6400 in your current rig and do everything aside from mass multitask just as good and game better. Avoid Nvidia 9 series as they are not dx10.1 and:
 
http://www.techpowerup.com/reviews [...] _GT/1.html
 
Ill be honest moving to a q6600 system now is a waste of money coming from what you are on now. Just wait for the next rush of cpu's to release they should be right along with some nice price drops and new GPUs as well.

Temperature and noise are factors that need to be considered.  I was running the same clock with a coolermaster gemini II, but with silent fans, i dont like my processor to ever break 60C.  If im gone for a couple weeks, i want to know my system - even if a ton of dust builds up - is not going to overheat.  Water cooling with the swiftech compact series made it extremely cost effective, stable, fast, and super quiet stuffed under the desk.  Temps with prime 95 peak at 55C with just the cpu in the loop and the compact 220 radiator with 2x silent 120mm fans.
 
I will likely push it later, but running memory and fsb 1:1 seems to make a little bit of sense.  3.6 9x400 was giving me crap, and at this moment i dont want to fiddle with it.  p5K-e with everything on auto.  

If you are going the Intel route I would consider an ATI card.  Nvidia just got busted for basically cheating on their revealed specs.
 
http://www.techpowerup.com/reviews [...] _GT/1.html
 
Depending on what you do an E8400 OR Q6600 may work well for you.  I think the X38 gives you a smoother ride with the higher native FSB speeds.
 
How long do you want this build to last?  Spending a little more now will make you more future proof.

overclocks well

it wil over clock very well. check out my sign.  
 
a good how to http://www.tomshardware.com/forum/ [...] erclocking

How about 400x8 with a Zalman 9500?