One way to do it is to go to "My Computer", and select your C-Drive. Then find one of the files that insists on opening with the wrong program.

Right click it, and pick "Open With....". Most computers will sit there a while after this, and then come up with a list of several programs you can open the file with. Hopefully, one will be Microsoft Word.

Select Microsoft Word, then check the box that says something like, "Always Use this Program...".

That should do it.

Of course, I'm still a bit out of the loop woth XP, but all the other versions of Windows work like this.

Good luck.