Is installing Win 7 on a new partition a much cleaner solution? (machine can run super fast)

"I'd recommend a clean install. When upgrading there will always be files, programs and settings left behind which could bog down your system. Doing a clean install, you know that there is no additional clutter laying around from a previous version of Windows and you can then copy over documents you may have saved to an external drive.

And yes, you can perform a clean install with upgrade media, as long as the underlying operating system is an installed and activated version of Windows. So to answer your question, yes it must be ""on top of Vista"", but it will not be the same as the regular upgrade process, it will erase it for you."