Power supply Question

[roadrunner2348]

I'm building a new PC and need to know how much poewr I'm going to need to run it. As of now I'm planning on getting a ABIT IC-7 motherboard, Pentium 4 2.4ghz 800FSB w/HT, ATI Radeon 9700PRO, and 512 DDR400 Ram. Will a 350W PSU be ok or will I need a 400W? Also I wanted room for upgrading so if I were to upgrade the CPU, Video card or add more ram what should i get now so I won't have to upgrade later. Thanks in advance.

 

[JZilla]

Excellent guide on psus over at Firingsquad.

Forget the wattage and keep an eye on the 12V rails. And do NOT buy a generic, buy Antec, Enermax, whatever they are called.