Can i install vista upgrade over windows 7? -

i am thinking about getting windows 7 beta but i want to know when it runs out can i reinstall vista with an upgrade disk

No you can not upgrade Windows 7 as it is newer than Vista. If you decide to install Windows 7, the only way back is to install a windows version earlier than Vista ( XP) then you can use your Vista upgrade disk to upgrade to Vista.

You might have problems upgrading backwards (i.e. to an earlier version). Your best plan would be to back up all the stuff you want to keep and do a completely fresh install - then put you docs and stuff back on.