Some programs are Windows-only, and so you can't get it for Macbook. Most programs (Office, Firefox, Email clients, etc.) either have a Mac version. With everything, even if no Mac version is available, there is some Mac program that does the same thing, as good as or better than the Windows version.
It works differently, so will take you a few weeks to get out of your Windows habits, and another few weeks to begin to see the Mac way of doing things. But it's worth it.
Suggestion: find your nearest Apple store (official one, not reseller), and buy from Apple themselves.
Finally, if you do decide to go the Windows way (for example, if you're into the latest games, then Windows is the only way), then you should get XP and not Vista. Avoid Vista like the plague.