ORIGINAL: naic7
To answer everyone who is having trouble running the realflight g5 demo, with windows 7 you now have to go right click and then go into the properties, from there you can chose to run the program as an administrator which will make it work. (I had the same problem).
Vista and Win7 SHOULD(it IS on my Win7) have Run as Admin on the context menu (right click)
XP had it buried in properties.
Check both places, for the properties in Vista and 7 it will be found on the Compatability tab, and this setting is a permanent setting.