Potatoman,
you shouldn't fret overly. Yes, your installation of Office may well be unlicensed.
But Microsoft are unable to tell that it is YOU who have it, and will not go through all the effort of getting a court order from your ISP to get them hand over your details, just to take you to court. It's not worth their time.
If it really is concerning you, buy a new copy from Amazon or Dabs, and install it over the previous Office installation.
(I wouldn't bother myself though!)