If your Windows came preinstalled on your computer it was already activated at the factory. If you installed Office 2007 yourself then you do have to enter the product key in order to continue using it past a very limited evaluation period. You
need to locate the product key on the dvd case inside the Office box. For other issues relating to activating Office, such as being continually asked for activation, you need to ask in an Office forum.
The specific forum you need is at
http://answers.microsoft.com/en-us/office/forum/office_2007-office_install?tab=all
That forum is for Office 2007 installation and activation issues. This forum is not for Office. It is for Windows 7 activation and validation issues.
Colin Barnhorst Windows 7 Ultimate x64 on DIY with 6GB ram.