Hello Suze68,
I assume that your copy of Vista came pre-installed with your computer. If so, who was the maker of the computer? All Large Computer Manufacturers (Dell, HP, Gateway...so on), that include Windows pre-installed, are required to include a Certificate of Authenticity that includes the Windows Product Key (usually in the form of a sticker stuck on the side or bottom of the computer).
Also, please download and run the Genuine Diagnostics tool at this link http://go.microsoft.com/fwlink/?linkid=52012. Click "Continue" click the Windows tab, click the "Copy" button, then paste the report into a response message in this thread.
Thank you,
Darin Smith
WGA Forum Manager