Building a new gaming pc

I would like to know what kind of stuff do i need to buy to make me a good/decent Gaming pc that will be able to run a few of todays games with out problem.

thank in advance

>>8
Hardly a rational argument.  I'd only go for AGP if I couldn't afford PCI-E.  SLI isn't a waste of money - I get almost double graphics performance from it - I can't buy a single card which will come anywhere near that performance.  It also means that if you're a bit strapped for casxh now, you just put one card in and get a second later.