A list of Microsoft Knowledge Base articles is available to help you troubleshoot error codes and error messages that you may receive when you try to activate Windows Vista

A handy link to have when you are troubleshooting activation issues with Vista, which, knock on plastic, I haven't encountered yet at home or in the enterprise space.

Bookmark the KB article listed here - KB 951287.

Official description:
When you try to activate Windows Vista by using the Windows Vista activation process, you may receive an error code or an error message. This article contains a list of Microsoft Knowledge Base articles that can help you troubleshoot these error codes and error messages.