See, I thought it had to do with what percentage they're supporting you. i.e. if you're 25 and live rent-free at home and your parents can say truthfully that you are dependant on them 50% (for me, that'd be pretty easy to prove - I live at home and don't make anywhere near enough to move out) they can claim you as a dependant.
But, I certainly don't have a degree in Tax Smarts
so I'd stop by H&R block if I was you. Plus there are a LOT of deductions for educational benefits, etc. you might not know about.