Tax exemption regulations?! Confused.. help?

I need help for my specific case please. For 2006, I owed 0. In 2007, I also filed exempt and owed $150 (I only made $6500 the entire year). I recently got a new job that I will keep for a few months, but I go off to college in early August and wont be employed. I expect to make $5000 or less. My employer told me I couldnt claim exempt... but I would rather not be withheld if I dont need it to be. Also, I am single, minor, dependent, and full time student. Help?!