Hi,
You can install office 2003 over office xp, any version. What office 2003
will do is detect your previous version of office (in your case office xp)
and upgrade it. What it also does is that it has a rollback feature, that is
if you want to uninstall office 2003 in the near future, then you can do so
and your office xp will be restored. But the only thing is that when you
upgrade from office xp to 2003, it saves the previous version on your hard
disk and occupies some space. I would suggest that if you are short of space
you should uninstall office xp during or before installation.\
Regards,
Harsh Bajaria