Hi Julian
"without any worries" may require some investment. I am running rFactor with an i7 920 @ 3.2 Mhz, 6 Mb of DDR3 SDRAM @ 1333 Mhz. Video card is an Ati HD 5970 with 2 Mg of memory. Running every possible setting at its maximum value including shadows, res at 1920 x 1080, with 24xAA (extended in CCP), Super Sampling AA, 16xAF and get an average of 170 frames irrespective of track. Some tracks are harder on frames, some are less demanding. Visual quality is astonishing.
Playing with resolution, DX mode and AA settings (both in game and CCP) I have been able to get over a thousand frames!!, with still acceptable graphics quality.
Running rFactor with a capable Dual Core, 2 Mb RAM, and a relatively modern graphics card (Nvidia GTX 2xx series and above or Ati HD 4xxx series and above) should result in a very playable game at almost every resolution with good graphics.
Regards
expdom