Contact your local Microsoft office to get a new key. That will be free.
Kees
i swapped my hardrive with a new one and i could not re-install my office 2007 'cos it kept saying that i have exceeded the # of times i can install it. Paid $399 for this in '07. HELP!!!!

Chowhound
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GameFAQs
GameSpot
Giant Bomb
TechRepublic