Hdrider you put in the CD of ZP and start the installation of XP. XP is "intelligent enough" (strange to say this of a Microsoft application) to recognize that there is an older windows version isntalled and will ask you if you want to update or if you want to set up a dual boot. You choose the dual boot and then it will do it all by itself. At least so it did when I installed my XP Pro as dual boot over a Windows Millennium installation.