It's a bargain and you get a license for cheap. If you feel you need the full license there is an option there.
Even the upgrade version often fails so let's just call it what it is. Upgrades don't work all the time so let's hope you have a few backups of what you can't lose.
I purchased the Windows 7 Pro student upgrade package from the Microsoft site only to find out that it doesn't work if I have Vista home premium. I saw a thread from 2009 but that was a different situation. I have Vista 64 bit. I can't believe Microsoft would sell students useless software. I don't want to do a custom install and have to reinstall everything. Any help would be greatly appreciated.