i hate all the people saying the 8600 sucks... if hes got a smaller PSU, and he doesnt game at high resolutions.. then yes a low-midrange 8xxx card is good for him. from what ive seen the 8600 preforms about the same as the 7600 series, and those were pretty good cards! my roommate plays oblivion with medium settings on a 7600.. so that 8600 would work just fine for him. plus it hardly uses any power.
People say that because it's true, also if you are building a computer geared towards gaming or any other type of intensive app, it is not recommended but demanded that you own a decent power supply not only to power your hardware but for the stability.
On topic, there's really nothing I can say... Kamrooz pretty much said everything I was going to say. Well, maybe I can try stressing a bit more how bad the 8400/8500/8600 series are, they are about as bad as dog poo or HD2600.