You don't need much
Since you are on a budget, we'll go with AMD:
Abit NF7-S Motherboard
Barton 2500+ Processor
1 GB PC2700 RAM
Radeon 9600XT Graphics Card
160 GB Maxtor Hard Drive
Generic Case
Generic Keyboard & Mouse
Lite-On DVD-RW
Lite-On CD-RW
Pick your brands for all of those that don't have one. Should be right around 1000 bucks if you choose
www.newegg.com.