that's weird. Have you tried if XP can see other file types created under linux - say a .txt file?
Also, can you see the .doc files when you just open the folder in a file browser (I guess My Computer -> A
? I once had a problem that Office wouldn't see doc files saved under linux on a dual boot setup even though the file browser saw them all right - and double clicking on it resulted in an attempt to open it using Word which then complained that the file does not exist... Never understood what the problem was and it went away after a reinstall.