http://www.rfactor.net/features/#sysreqs
Runs Best With
Intel Core 2 Duo E6600 processor
Windows XP
2048 MB RAM
Geforce 7900 GT or Radeon X1900 GT
256 MB video RAM
DirectX 9.0c
2.0 GB of hard drive space for installation
Internet connection required for one-time activation


System Requirements
1.4 GHz processor
Windows 98 SE, ME, 2000, XP, XP 64-bit, Vista (will NOT run in Windows 95 or Windows 98 first edition)
512 MB RAM
Geforce4 4200 or Radeon 9200
128 MB video RAM
DirectX 9.0c
2.0 GB of hard drive space for installation
Internet connection required for one-time activation

Note that if you install a mod/addon that uses more resources, that can affect performance.