What can I delete/uninstall?

Hey, just got a new mbp sr 2.2ghz and was thinking about either bootcamp or maybe parallel soon, but i realized that will probably take a good 25 gigs up with everything, is there anything that I could definitely clean off my cmoputer or does os x and everything it comes with just take up around 17 gigs ish. (not sure if this is the right forum, maybe should be in os c)