I now run FSX and FS9 on Win 7 RC and in a week it's time to install the commercial Win 7. Then when reinstalling FS I would like to install FSX with its addons before FS9+ its addons.Reason for this is that I have much more work to do with FS9 with significantly more addons. But I think I have heard rumours about problems with installing FSX first. Or is this nothing to worry about.

I now run FSX and FS9 on Win 7 RC and in a week it's time to install the commercial Win 7. Then when reinstalling FS I would like to install FSX with its addons before FS9+ its addons.Reason for this is that I have much more work to do with FS9 with significantly more addons. But I think I have heard rumours about problems with installing FSX first. Or is this nothing to worry about.

They are 2 seperate programs, just be sure any addons you install point to the correct version, some are designed for both.

Had no problems on Vista 64, but this was just the FS itself, no addons for compatibility testing. Installed FSX RTM, sp1, sp2, then FS9, 9.1 update to the default locations. I do have UAC turned off on the system, don't know if that makes a difference. All Vista 64 sp/updates installed except for some optional like silverlight.scott s..