FYI - I had a version of XP Pro on my system and no box or CD. To get legal I bought an "Academic" version of W XP Pro Upgrade for $82.00 (my daughter is a student) from a "major" web site. I installed it as a "Repair" with no problems - followed by SP1 and am now legal. I did not have to reinstall anything and all settings, passwords and other "stuff" carried over.