I have used AA9 that was setup on my Win7 machine from the start. However, it was a 32-bit system. So the only problem I see might be issues with the 64-bit system. It might be that the print driver and AcroTray may not work on a 64-bit system (probably need 9.5.5. for sure). Why not just try. Other than that, it should work fine. I have even run AA7 on a 64-bit Win7, but did have an issue with the 2 files just mentioned and had to develop a workaround. I only did it as a test, not an intended use.
Bill.. thanks for the input... I've since managed a Chat with Adobe personnel, and presumably, because the 9.5.5 version was originally downloaded, registered, and activated, I can deactive on my old system, download to new system and activate... and hopeuflly during the process the installer will recognize the platform and install the right version...I'll find out when I receive the new system...I guess worst case, I'll need to pay at an upgrade price...thanks again..
If you did not create an archive of your old download, you will have to deal with a process like mentioned in http://forums.adobe.com/thread/1061905 to get the download again. The downloads are not maintained for older versions in general.
Bill... thanks for the tip.. this reminded me that I did archive this software version on Google Drive.... so I will download the archive on my new system and install; presumably it can handle the new OS environment....