You have some options here... if you have illustrator cs2 you can use the live trace feature (which I don't really like). If you don't have cs2 you can try adobe streamline (which I also don't like, I would call it an older version of live trace... because that is what it is, haha). And finally, the best way is to trace it yourself using the pen tool. Time consuming but for sure the best way, for a tutorial on how to do this visit the link in my sig and check out the video tutorial for "intro to the pen tool".
Good Luck!