Office 2003 and Office XP are not "really" compatible. Damn Microsoft with the infinite number of variations and patches for their products. I have Visio 2003 and Visio XP. The file I save in Vision XP can be read from Visio 2003, but not the other way round. So I guess that the 2003 suite is actually newer than the XP suite.

I am no Office expert so I can not help you. Good luck with your quest for the truth nevertheless!