dave.green1
Actually there is a way to load different services. However, not in the form of different users, rather different hardware profile.
Follow this link, http://www.blkviper.com/WinXP/xpprofiles.htm and it will show you exactly how you can do that.
That website, http://www.blkviper.com/index.html also has many in depth explanation of all the services. It's a great site.