When upgrading, it’s usually best to back up all files and perform a clean install of the new OS.
My w7 upgrade shipped this morning so I'll have it in a couple days. I have plenty of excess disk space to fully backup and install clean but I'm not sure whether or not it's worth the effort (I back up my info already.)
Any stories of real world experience going from Vista x64 to w7 x64 would also be appreciated here.