Found a nasty gotcha today in Office 2003 SP3. There is a new group policy setting that controls whether you are allowed to open documents from previous versions of Office. However the default is No. You need to create a group policy to allow it. We have two customers already that simply didnt know that a heap of word and excel docs were in a previous format until they couldnt open them.
Thanks to Daryl Maunder of the Melbourne SBS Users Group for posting that one.