All depends on your budget, however, if you aren't going to play games, something like this would be good:
CPU: Core 2 Quad Q6600 (or C2DE8500)
Mobo: Gigabyte GA-EP35-DS3
RAM: 4GB DDR-800
Graphics: 256MB ATI Radeon HD 2600XT
Hard drive: 2x1000GB Samsung (or 2x500 to cut on cost) in RAID 0
A...