Manuele --
As stated above, FS9 is a 32bit application, and should run (the word is SHOULD) from the path it chooses at the initial install. This is not always the case tho. Win7 can be a bit picky about things. Had you previously un-installed FS9 and then tried to re-install it on this machine? What I would do is this...
Un-install FS9 completely, then use a registry clean-up tool such as the free version of "CCleaner" and run it to make sure it takes all of the incomplete entries for FS9 out of the registry. After that, try re-installing FS9 using the path that lemonadedrinker spoke of, or the one I use. It should work just fine.
You may get the pop-up that says that the program didn't install properly, but I would try running the new install of FS9 FIRST, just to see if it works, before un-installing and re-installing it using the "Compatibility Mode". Also, depending on your anti-virus program, you may want to temporarily shut it OFF just long enough to complete the new install, then re-activate it when you're done.
BB686