Hi Mark,
It might be the only way but is there a time limit? Before ruling Norton out, I spent hours on the phone doing various test emails; uninstalling re-installing etc. so be ready for a big phone bill.
By the way, the other aspect is not being able to do a clean un-install for Office although you may be better placed to do that on XP. That is what I would try first in your position. Unfortunately the MS procedure for clean uninstall doesn't seem to work on Win 7