after it's been installed you have 30 days to activate it.
the first time it easily activates over the internet, after that it askes you to call customer service for activation.
call CS read your serial # off to the computer, and it will get a cust service rep.
then you tell the girl that it's only installed on one computer and she will give you the new conformation number (WRITE IT DOWN BEFORE YOU CLICK NEXT to avoid having to call cust service next time you format) she will tell you to click NEXT, and then the conformation number is gone until you call cust service again.
it's not really protection from people using one copy on multiple computers, but calling in to cust service scare off most crooks. they dont even ask for your name, just your serial number, and how many pc's this copy is installed on.
I would recomend you buy a copy, but dont pay $90 bucks for it.
I found that the student book store at University of Alabama in Birmingham (UAB) sells XP Pro to students (not the student version, just only sold to students) for $5.25 and XP Office pro for $10.25 (2 discs)
keep in mind that University of Alabama in Tuscaloosa also sells a "Student Version" that cost about $85. it's not the same thing, keep asking around until you find someone local that sells it cheap. I think the UAB license says for students on campus only on the lisence, but my copies work fine (I went ahead and bought 3 copies so I would have one for each, $15.75 was quite resonable).