How do you make a copy of Windows from your computer so you can use it on a different computer?

A virus started to infect my computer and it was causing some of the SYS APPS to become unacessable to me(not authorized)but the widows XP sp2 Cd that came with the compuer cant find the necessary files to complete the reinstallation of windows. can I somehow copy WindowsSP3 from a different computer and use that one? If so, HOW?