Why using MS Office 2007 with SharePoint 2007?

If you are using SharePoint 2007, why should you upgrade from MS Office 2003 to MS Office 2007?  Here is a list of the additional end-user benefits realized when interfacing with SharePoint 2007:

http://blogs.msdn.com/brittog/archive/2007/02/16/wht-you-get-with-office-2007.aspx

Another good article on this topic: MS Office Integration with SharePoint [Fair, Good, Better and Best]
http://www.sharepointbuzz.com/2007/04/18/ms-office-integration-with-sharepoint-fair-good-better-and-best/