I bought all my components based on your recommendations. I'll be using an Nvidia FX1800 for my GPU, which I believe will be a good match for this system, and for the software that I intend to use. Got everything in and I'll be assembling it this week. Your advice was a big help in my going forward with this project. Thanks again!
I don't know much about workstation GPUs, so you might need to find help on that somewhere other than me. Do you need an OS?
Mobo: Asus P6X58D Premium
RAM: G.Skill Pi Series 3x2 GB 1600 mhz CAS Latency 7
HDD: Samsung Spinpoint F3 1 TB
PSU: Corsair 750W 80+
$90 after rebate
Total: $969 w/o GPU, OS. Grab the best GPU you can afford. Windows 7 Home will cost $105.