Current:

AMD Athlon XP 3000+ (clocked at 2.2Ghz)
1024 MB RAM PC3200 (400MHZ)
Sound Blaster Audigy
Nvidia Geforce 6600GT 128MB

Upgrade:

Intel Pentium D Processor 930 - 3Ghz, 2x 2MB L2 Cache, 800MHZ FSB)
1024 MB DDR2 RAM 533MHz
256MB PCIe Geforce 7300 TurboCache