Is your MacBook Pro new enough to have an Intel processor or is it still a PPC chip? If it's Intel you could go to 10.6 in the same way - buy a retail copy. If your chip is the old one, 10.5 is the limit of your upgrades.
Thanks Doctor X, that wasn't very helpful.
I bought this macbook pro in 2006 but it lay dormant under my bed until 2008 because I had a PC and used that instead.
I would think that Apple would put out a download vs forcing me to get a disk to install this but, maybe I'm wrong?