Windows Vista Home Premium is the operating system installed on your Acer laptop. It's very likely your Microsoft Office 2007 application is only a trial version. To continue to use the Microsoft Office 2007 application after the trial period has ended, you'll need to purchase a product key for it.
Please see the following:
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/927756How to buy Microsoft Office 2007:
http://office.microsoft.com/en-us/suites/fx101678741033.aspxNote: The product key located on the bottom of your Acer laptop is for the Windows Vista operating system and not for Microsoft Office.
Carey Frisch