Hi Joshmayer
For registry cleaning I use CCleaner (You can find it as free download on the web) and it seems to work very well, then You have to delete the folders C:\Documents and Settings\"your user name"\Application Data\Microsoft\Combat Flight Simulator 3 and C:\Documents and Settings\"your user name"\Documents\Combat Flight Simulator 3 (this is if You use XP, for Vista is a bit different but I don't know it exactly) this AFTER You run the CFS3 uninstaller, of course.
Hoping this can help You
Cheers :ernae: and have always good flying
Cristiano "Astore"