Hello UMTaz,
The reason your Key is not working is because it is an Upgrade Key that can only be used to Upgrade.
I am assuming that when you re-installed Vista that you didn't first reinstall Win2000, so that Vista could upgrade from it. So, since there is no Win2000 to upgrade from, you didn't do an Upgrade install and the key only work for upgrades.
Now, that being said, there is a workaround that does not involve reinstalling Win2000, please see Carey Frisch's July 31st post in thread
http://forums.community.microsoft.com/en-US/search/?q=carey%20clean#page:1;sort:lastPostDesc He references a Web Page that give a very good write up on how to conduct the workaround.
(Note: I would just post the URL, but it leads to a website that Microsoft has no affiliation with and we are not allowed to endorse or promote non-partner sites)
Hope that helps,
Darin Smith
WGA Forum Manager
Attention Forum All Users: Please Do Not post your issue in someone else's Thread...Create your own.