What are the system requirements?

(For OFP: Resistance, look here).

Officially, as printed on the package, it says:

Minimum Requirements:

Windows 95/98/ME/2000
DirectX 8
Pentium II 400 CPU
64MB RAM
16 Bit DirectX Sound Compliant Sound Card
Compatible 3D graphics card with 16MB RAM (8MB if using a Voodoo2)
8x CDROM
450MB Hard drive space

Recommended Requirements:

Windows 95/98/ME/2000
DirectX 8
Pentium III 600 CPU or better
128MB RAM
16 Bit DirectX Sound Compliant Sound Card
Compatible 3D graphics card with 32MB RAM (8MB if using a Voodoo2)
24x CDROM
450MB Hard drive space

While Codemasters says that 128MBs of RAM is recommended, if you have 256MB or more, you'll most probably enjoy improved and smoother game performance.

Note that, even though it's not listed, Windows XP is supported, too.

Supported 3D Chipsets:

3DFX Voodoo2, Voodoo Banshee, Voodoo3, Voodoo4, Voodoo5
ATI Rage 128, Radeon
Matrox G400, G450
Nvidia Riva TnT, Riva TnT2, Geforce 256, Geforce 2MX, GTS, ULTRA
S3 Savage 4, Savage 2000
3D Labs Permedia 3
PowerVr Series 3 (Kyro)