yeah so you can save all your stuff on cd/dvds and then do a clean install, and its not to see if it works, it WILL work, like i said ive installed vista last week and ive had no problems saving anything, nobody should really, so all i can think of its something Dell did by accident or something

If you havent got a vista disc then you can jot down your serial number(right click my computer icon, go to properties and then look near the bottom for the product ID) and then just download vista from the torrents, install it and use your serial number on it.

If you dont fancy that you could just buy a disc for £60 http://www.ebuyer.com/product/123052

It is honestly sounding like you have 2 options though, ringing Dell and getting them to sort it or reinstalling windows