Hi BOnez2k6,
You, to re-activate your copy of Vista, you will need Activate by Phone (see steps below). Please note that is you decide to re-install XP instead, that you will, most likely, be required to re-activate it by phone, as well.
Click the Start button, and type in "slui.exe 4" in the search field and then press the "Enter" key. This will bring up the Activate by Phone dialog window. Follow the steps provided by the window.
NOTE: The key to this process is that you need to talk to a Live Activation Rep! When you first call, you will be interacting with an Automated Voice, either select the option to talk to a Live Rep or if there is no option, do not enter any numbers. This should force the automated voice to tansfer you to a Live Rep.
Thank you,
Darin Smith
WGA Forum Manager