Just got a new PC--Dell with Vista Basic. I immediately downloaded and installed Windows 7. I did not activate Vista before installing Win 7. I have tried several times to activate Win 7 but it will not accept the product key number on my PC. I get a message to the effect that the key is not valid. Is there a way to address this that doesn't involve uninstalling Win 7, and reinstalling Vista in order to activate it before reinstalling Win 7? Thanks!