Lynn, I've looked into this, since my Vista started to act weird a couple of months ago. Fortunately I tried doing a "system restore" a couple of times, and it seemed to improve. I then had a problem with Windows Update failing, and got Microsoft involved (they will do this for free when it's an update problem.) Turned out I had a malware virus, but now I'm clean. Make sure you Update is working properly.

As for the Windows 7 upgrade, you can run a program that will scan your computer and give you a report on potential upgrade problems. You can them prepare by uninstalling certain programs that will have to be re-installed later. In my case the only one reported was iTunes (not the music, just the program.)

I haven't done this yet, since I have been dealing with these virus issues. Somehow I have lost the link to this tool, sorry, but you should be able to find it by browsing after googling "windows 7 upgrade".