i would'nt spend 100 clams on realflight basic, when you can get the full version of 4.5 on the forums for that. heck if you running an outdated pc, then you need phoenix rc sim.

as a side not, i did run realflight g4 on an older pc a few years ago.

it was a hp pav m7300e
single core amd athlon4000+
2gb ram,
160hd,
450watt psu

and a nividia 8800gt video card with 512 onboard ram, ran rfg4, and 4.5 upgrade seamless. very smooth. hope this helps a tiny bit.