Here's just part of why. Read http://forums.cnet.com/5208-6132_102-0.html?threadID=119247
You have too much to lose here. While you can uninstall, Windows hides too much in places many don't know about. Just wipe the drive and gift it blank as a fresh sheet of paper.
Bob
Can this be done. I am giving away PC but would like to hold on to software. License is only for one PC. (I have installation CDs)
MS Standard Edition (French)
Merci d'avance,

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic