Markkevin,
In such circumstances, just rerun the Activation Wizard but choose the option to Activate your product over the telephone.
http://support.microsoft.com/kb/307890
That oughta do it!
PS: Instead of reinstalling all the time, why not make a drive image after a full clean installation, and the next time the computer crashes, just rstore the image...much faster than a full installation.
Use drive imaging products such as Acronis True Image, Ghost, or the free DriveImageXML.