Hmmmm, sounds like a pain to rename a bunch of files.
There may be a utility that can rename all the files that are in your website. I know dreamweaver has this built in, I guess I am lucky that I don't have windows XP at this point.
Maybe download.com will have something to help change the names.
Or like you said a XP user might know how to tweak the settings to recognize the pages.
Wish I had a better answer