If you need tips on what parts are worth your moneys just ask, I *edited*ing love building PC’s.
So… what are your specifications?
Intel – AMD
Dual – Quad core
Mobo: Are you interested in multiple GPUs?
SLI/CrossFire – Single Card
Nvidia – ATI
Good – Great – Crysis Killer
2G of RAM is plenty, If you really want to, you can go 4G
Vista is now fairly good, 64 bit and DX10 help emensely with gaming
Power Supply will depend on what parts you get
When it’s built, use SpeedFan to keep an eye on your CPU temps and load.
Let everything idle for a while then set the temp’s it is reading as the normal operating temperatures
If it gets too hot, get an aftermarket cooler like Zalman, godly coolers.
But yeah, I would love to help you build a computer.