How old are you? Just out of highschool, or have you finished college already?
If you havn't gone to school yet, don't do it. If you're short on money, go to community college first two years then transfer to state school. If you grab instate you're looking at $1200 max a semester for FT. This is still a chunk of change, about 10 grand worth, but can easily be paid off with a weekend/pt job such as bartending where you'll be able to also start social networking for future employment.
Once you sign that contract it's over. If you're all patriotic and want to shoot guns and kill shit, fuck yeah - go for it. If it's about school, there are other and better methods.
Plus you'll be in a 24/7 sausage fest in the service.