Do not forget, it is EXTREMELY important to check all the voltage outputs on the power supply like everyone has been saying.
For instance, I had a cheap-o $40 power supply I picked up in an emergency cause my old one had died. It was 420 watts. Problem was, it came with a total of 5 power connectors (4 molex, 1 floppy) and had a very anemic 16A on the critical 12V line. My old video card with this power supply was a GeForce 6600GT , and the old CPU was an Athlon 64 3000+ .... well needless to say everytime I played a game .. could be 2 minutes in or 10 minutes in, the thing shut itself down and reset the computer.
So I went online (yes, the exclusive Internet!) and read up a bit. The wattage matters of course, but it is not ALL that matters.
I ended up finding a Antec SmartPower 350W at BestBuy for like $35 on sale. Its a great power supply.... 25A on the 12V rails. Here is what it is running:
ABit KN8 Ultra
AMD X2 3800+
2 gig RAM
2x 160 gig Samsung HDD's in RAID 1
eVGA 7600 GT KO
Plextor DVD RW
Toshiba DVD ROM
Like I said, great power supply. Its prob nearing its limit now, but seems to be doing fine and I play Star Wars Galaxies and Battlefield 2 with it pretty often.
Check it out here, it may fit the bill.
http://www.antec.com/us/productDetails.php?ProdID=26350
(sorry if that link isnt clickable, I hate html)
Torgo
The Master Would Approve!