Hello tami.smith,
Computer manufacturers often install a trial version of Microsoft Office. If you are getting a prompt to type in a Product Key when opening a Microsoft Office program, it is likely the trial period is over and you'll need to purchase a license (product key) for Microsoft Office.
The product key affixed to your computer is for Windows Vista (the operating system) and not for Microsoft Office.
Please review the following for additional information:
How to determine whether you have a trial edition of a 2007 Office suite or program installed: http://support.microsoft.com/kb/927920/en-us
How to convert a trial version of a 2007 Office suite or program to a full retail perpetual license version: http://support.microsoft.com/kb/927756/en-us
How to buy the 2007 Microsoft Office suites: http://office.microsoft.com/en-us/suites/FX101678741033.aspx?ofcresset=1
How to Buy Office Home and Student 2007 Edition: http://office.microsoft.com/en-us/suites/FX101674081033.aspx
Thank you,
Darin MS