It depends on quality. In your case I´d say a 300W PSU of good quality would be enough (Antec, Enermax or Codegen). Low quality PSUs will make modern systems very unstable if using multiple drives and powerful graphics.
A large number of stability issues in modern PCs is due to an inadiquite power supply. Personaly, for $50 or so, a 380W Truepower PSU is a great investment, and might outlast the rest of the computer. Also, they help with heat (A more powerfull PSU doesn't heat up as much, as it's not straining as much, and they often have an extra fan), and can help with noise (Some have fan controlers that are tempurature sensitive, and the extra fans help them run both fans at slower speeds). Trust me, Slvr Phoenix, and Crashman (Check his sig), a good PSU is a great investement, and well worth the money you pay.
And after all, why spend a veritable fortune on the PC to get a powerful CPU, a powerful video card, useful (but power hungry) IDE devices and expansion cards, and then power it with a PoS power supply?
A rock-stable power supply prolongs the life of the hardware. Lower temps (helped out by power supplies that don't run as hot and/or have two fans) extend the life of the hardware. And the less your power supply is taxed, the more room you have for expansion before you have to upgrade your power supply.
So the way I figure it, if you can spend a ton of cash on a new PC, do all that you can to make sure that PC is going to last. Get a good power supply. It might not be an instant gratification, but in the long run it's more than worth the little extra money.
Ahem... anywho... I'm running a 300W with a similarly 'quipped system, and so far so good. It's an Antec, so of course one expects quality, but I'm thinking that the next thing to invest in is a TruePower. For less than $100, I can get a 430W, which, I would hope, last me at least 3 years.
8-Bit Theater rocks. It reminds me sooooo much of my old gaming days. (Not that I wouldn't mind some new gaming days, but driving two hours a day on top of 9 hours of work leaves very little time for both a decent dinner and a proper gaming session.)
It's actually nothing to do with PC hardware. It's an on-line comic based on a combination of role-playing-game stereotypes and some old graphics taken from the original Nintendo version of Final Fantasy 1 mixed in with some modern artwork.
(Since the NES had an 8-bit graphic engine, this is how the comic got the title of 8-Bit Theater.)
Just click on the link in my sig to see what 8-Bit Theater is all about. Maybe it's just because I was a RPGer, but I find the comic hillarious.