How do I change back from Windows 7 to Windows Vista?

[QCEdward]

I installed [url=http://www.windows7-key.ca/]Windows 7 Enterprise Product Key[/url] on my current [url=http://www.windows-7-key.us/]Windows 7 Professional[/url] computer, but it turns out I'll be getting a new [url=http://www.office2007-key.org/]Office Enterprise 2007 Key[/url] next month. The [url=http://www.office2007-key.eu/]Office Pro 2007[/url] guy said that I have to option to uninstall [url=http://www.microsoftoffice2010key.net/]Office Pro Plus 2010 Key[/url] and deactivate the key so i can install that same [url=http://www.office2010-key.ca/]Microsoft Office Standard[/url] on a different computer. How do I uninstall Microsoft Office 2010 and deactivate the key?