Well, we'd all like iron-clad guarantees, but that isn't the way real life
works:-)

It's well documented just about anywhere that Office 97-2003 core
applications (Word, Excel, PowerPoint) use the same *file formats* but it
doesn't necessarily follow that *any version* can open *any file* created by
*any other version* without *any possibility* of "incompatiblity" to *any
extent*.

What exactly is the objective - and were the files created using 2002 (XP) &
the concern is about upgrading to 2003?... "Office XP could work with Office
2003 format" is far too vague & gives no indication of which direction is
actually meant.