I think I did this once before a couple of years ago. I'm making a new system on the cheap. Tell me if I'm making a mistake. I have monitors, hard drives, dvd-r, and all that jazz, so I'm just buying the core components. Here's what I'm going to buy (you'll notice some of it is off-brand):
1 Intel Pentium E2180 2.0GHz LGA 775 65W Dual-Core Processor
$69.99
1 GIGABYTE GA-EG31M-S2 Micro ATX Intel Motherboard
$56.99
2 Kingston 1GB 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Desktop Memory
$39.98
($19.99 each)
1 CHAINTECH GeForce 8600 GT GSE86GT-A1 Video Card
$25.00 Mail-in Rebate
$74.99
Grand Total: $247.93