The PSU's that regulus recommended I would also recommend...cheap and a very good company. 480w for $55 you can't beat it....I have the 560 Thermaltake myself and couldn't be happier with it.
I couldn't be happier with mine either. Think I'll use it till' one of two things occurs: 1. It burns out. 2. The rest of the system burns out/explodes/something bad happens, 'cause the 480W isn't enough to support it all. lol