[petek]

You can have multiple versions of Inventor installed on one PC. Until recently I had versions 5.3, 6, 7, and 8 all on my machine at work, without any problems. The application does re-register with Windows when you switch versions, though.

From the Voice of Experience, one thing to watch out for : If you have v5.x installed and uninstall it, be sure to delete the folder containing the "Content Library" files for that version before you install a more recent version. Otherwise the installer doesn't correctly install the content library for the new version and things can get messy. You shouldn't have this problem if you just leave v5 installed, though. (I found this out the hard way by deciding to get rid of v's 5-7 before installing v9. Now whenever I launch v8 or v9, I get a not quite functional dialog asking me to find the content library.)