I have mine installed on XP....but it wasn't easy.......

I had a really tough time, because I had the OLD version of realflight...then I bought a G2 upgrade disk......so I had to get the OLD version to install on XP first (that was interesting), THEN upgrade to G2. Since I had the old version, with an upgrade, Realflight support was pretty much non-existent.....all the info that they had dealt with installing G2 only. Once I got everything running, installing the add-ons was interesting too.....

It's been 2 years since I installed mine, but I seem to remember having to change the Realflight program to emulate it running in a Windows 95/98 environment.........I did a bunch of searches on the net and came up with this....