I am almost positive about this for my new build:
 
Mobo:Gigabyte GA-P35-DS3L
GPU:Some 9800gtx 512mb
Ram:4gb 2x2gb (not sure what kind)  
Case:Antec 900
Optical Drive:Maybe two
HDD:320gb
CPU:Q6600 @ 3.2Ghz w/ Xigmatec HDT-S1283
I also want to get 2 12in cold cathode lights
 
My question is...what PSU will I need? Thanks

something strong but it doesnt have to be massive
 
Corsair520,620 or  750
Antec Trio series
PCP&C have a nice 610w model

With what you list, a PSU of 450wt-550wt should do fine. A Seasonic, Antec Earthwatts, or similar should fill the bill. Check under Forums, power supplies, and tier listings for recommendations on specific brands.

Depending on if you oc or not, and psu 12v rail ratings, you should get more than 550watt. It should do, but it's always better have spare room when it comes to those things.

Running what the OP listed through the eXtreme PSU calculator shows a power use of 432 watts. Add 20% for safety and that comes to 518wts. As a result, a 550wt should power what is listed quite well with some room to spare.  
 
If more hardware is wanted, then up the size to around 600wt, as Chookman suggested. But there's no need to get a massive size PSU.

65nm quad overclocking eats up a lot of power, better make it 650 watts just to be sure.

Actually, dagger, you'd be surprised.  
 
I was curious one day. I borrowed a clampon ac/dc ammeter from work. A Q6600 overvolted enough to run at 3.3 GHz pulls about 9 amps through the 12 volt EPS  plug.

I'm with Sailor and Chookman on this one. Look at my link in my signature that takes a e6600/8800gtx (g80) and both are OC'd and it runs on a 380w Antec Earthwatts PSU. Now I wouldn't run that setup for too long, but goes to show you what a quality PSU can do, which is what Sailor/Chookman listed. Now the Antec 380w PSU has 27A on the 12V rails, so the Corsair vx450w PSU has 33A on the 12V rail, so would be plenty for what he wants to do. Yes the 500/550w PSU would leave more wiggle room, but the build doesn't require a 650w PSU. I just don't see spending extra $ on the PSU as long as you get a quality one. At the rate your stating things, you'll be recommending a 1200w PSU for good measure.

Ok. I think I'll go with a good 550w. But I want Corsair, PCP&C, or OCZ, or another good brand. I am for sure on OC the Q6600, but I kind of have the feeling that I am going to want to OC the GPU also, but I probably wouldn't need to though. I was going to get a 8800GTS but I have decided to go with the 9800GTX because of the new 9900 series coming out in I think July, and I don't want to have to upgrade for a while. Well, Thanks.

EDIT: What is a good one?

550watts should do fine. But personally, I don't think it's comfortable enough of a head room. Why skim on psu when you've poured so much money on the system? It's just opinion though.

I'd advice against taking the 9800gtx over g92 8800gts. Look at this:
http://en.expreview.com/2008/04/03 [...] review/12/

Use the 8800 for now, and consider getting 9900 series, depending on how they perform.

Here you go, you can decide what ya want. They are all good and of good quality.
$85 shipped! Has 41A on the 12V rail and 5 yr. warranty. It comes with 1 x 6Pin, 1 x 6+2Pin so you will have a 1x6 pin and 1x8 pin PCI-e connectors, which comes in handy when you need a 8 pin PCI-e connector for the GPU.
Corsair VX 550W ATX Power Supply - CMPSU-550VX
 
$110 - $20 MIR = $90!! A steal for this one!! 52A on the 12V rail and has 5 yr. warranty! Has 2 x 6+2Pin PCI-e connectors, which means you can have 2 x8 pin PCI-e connectors! This will come in handy later, when more GPU's require the 8 pin connector.
CORSAIR CMPSU-650TX ATX12V / EPS12V 650W Power Supply 100 - 240 V UL, CE, CB, TUV, FCC, CCC - Retail
 
$110 shipped!! 49A on the 12V rail and 5 yr. warranty Comes with 2 x 6 Pin PCI-e connectors. Will need converter connectors to get an 8 pin PCI-e connector, which might/might not be important to you.
PC Power & Cooling S610EPS EPS12V 610W Continuous @ 40°C Power Supply 100 - 240 V UL, cUL, CE, CB, TUV - Retail
 
On the GPU, I'd probably go with the 8800gts (g92) and just OC it to 9800gtx speeds, or pretty close to it. Than when the newer ones come out in 2-3 months, I'd use eVga's "Step Up" program and upgrade to the latest GPU's.

What is the Step Up Program? I've heard about it. But that would mean I would have to buy an evga. Which dont they offer the warranty even if it was overclocked?

 
Why spend money on a trademark for a powersupply? Corsair, PCP&C and OCZ just slap their trademark on a powersupply that meets their minimum quality specification that is manufactured by a company that provides the lowest contract bid to make the powersupply. It's business. It's profit margin. Companies don't give a crap about the customers. The only time a company takes notice is when their outsourced inexpensive product fails to meet minimum quality standard and the customers start complaining about product failure.
 
Generic name powersupplies made by oem companies for Corsair, etc. are Sparkle and HighPower.
If you don't want to go with a whitebox powersupply then take a look at Antec powersupplies. They're not overpriced like powersupplies from OCZ, etc.
 
If you need to have a name brand powersupply then the Antec TruePower Trio 550 will meet your needs.
http://www.antec.com/us/productDet [...] odID=23550
You should be able to pick one up for $80.  
 
Corsair 550W $90
PCP&C 610W $112
OCZ SLI Ready 600W $103
These are the lowest prices I could find from on line stores that have retail sales outlets where I live. I don't like having to pay shipping fees and shipping insurance if I don't have to.  

I believe the Corsair vx series (450-550w) are made by CWT and the hx series (520-620w) ones are made by Seasonic. I don't think either one of them makes a bad PSU. Yes they farm out to whatever PSU manufacturer that meets their guidelines, but with a 5 yr. warranty, it helps. I'm not saying that the 5 yr. warranty seals the deal, but it should be considered when purchasing a PSU. I know the Ultra PSU's have a limited lifetime warranty, but you won't get me to buy one right now. This is just a personal preference and not any reflection of the company. I've just read too many posts that have had issues with at least the older Ultra's, so I tend to stay away. This also doesn't mean that other "quality" PSU comapnies have had or still have iffy designs, but this is just something to consider. If you do your research on your parts, you will feel better about your decisions and hopefully will have quality parts that don't go south on you.
As far as getting PSU's online and paying shipping/taxes, most of the time I look for a PSU locally, they either don't have what I want or it is too expensive. So I tend to buy my parts online, since they usually have what I need and have it for quite a bit less than a local shop. To each his own. Hopefully that helps you in your decision.

One of the things I look for in the specs is:
"Full rated power at 50 deg. C."
 
That is such a difficult specification to meet, that anyone who can, will tell you.
 
The PSU's in my two newest boxes are Antec's - 650 w TP3 on sale 30 % off and 550 w TP3 on sale 45% off.
 
I also try to keep the load on them under 70%.

I've decided to get a 8800gts G92 512mb and a 550vx. Maybe I can get a deal on them somewhere soon.