Just found this article. you probably just need to uninstall on the computers that you can and then install on the new computer. You can't deactivate but just not have multiple machines running at the same time.

here's two posts I found. One on a MSFT forum and another is a KB article.

http://www.microsoftoffice2010forums...-7#comment-397

and

http://support.microsoft.com/kb/927921