Minimum:
CPU: Pentium IV 1.7Ghz - 128Mb (or equivalent)
Video: 
NVidia: Geforce2 or higher required
ATI: Radeon 7500 or higher required

Recomended:
CPU: Pentium IV 3.0Ghz - 512Mb (or equivalent)
Video: 
NVidia: Geforce 7950GT
ATI: Radeon  X1950

SiS, Intel and S3 cards might or might not be supported. Always use the latest drivers provided by your graphics card vendor! (unless a certain driver version is known to give problems)