Just another tidbit of info. M$ will not be comming out with DOS for XP. That would be the exact opposite of what they are doing. I havent heard(albeit supprisingly) that many problems with Dos programs in XP. What likely is happening is that thesoftware is old enough that its trying to access hardware directly and thats a big NONO in NT. You may have a simpler recourse by right clicking on the programs icon(may need to be the .exe and not just the shortcut) and you should find an option to run under compatibility mode. Try putting it on Win95(as im sure DOS is not an option). IF this simple option doesnt do it than you may need to create a DOS partition like the first post said.
Hope this helps
Jason