I take a 7 in 1 cd with XP Home/Pro/Corp/MCE , 2000, and 98 (which I googled to find for downloading) on it when I go to visit customers site as some seem to never know what flavour of windows they are running. I select the appropriate version and then enter their code in. I have done this on Dell, Gateway, HP, Compaq, Emachine, and custom builtcomputers and without too much difficulty aside from some driver issues once the basic install was done. Also can be used to do recovery or resetting admin passwords when all seem to be locked out of loggin onto their accounts. Hope that can help you