Running Windows on a MacBook Pro 17"

[Riskwise]

k i talked to someone about my previous question and got it answered, now i just need a single disc install of windows XP with sp2 already on it, no update CD or earlier version allowed.

Does ANYONE know what you have to buy to get this CD?
Because i have a ton of friends getting college laptops and they all seem to not get the actual windows xp install disc with it somehow. Is purchasing windows XP at a store the only way to get the disc, or should at least someone i know have it who recently purchased a new computer?