Additionally one key element is the rigor of your course curriculum. Is the 3.5 weighted or unweighted? Have you taken all Honors or APs or are you taking standard courses?
They look at the WHOLE CANDIDATE. That not only includes your academic stats, but your ECs too. You need to be well rounded, not just great in one aspect and nothing in the other.
Also, it is important to start understanding how each branch works their ROTC scholarships. The NROTC and the AROTC are linked to the schools you apply to for admission. This means you can get admitted to the school, but not get a scholarship, and vise a verse, you can get a scholarship, but not get admitted.
The AFROTC scholarship program does not work that way, it can be taken to any school that is on the AFROTC list. However, as you will see through these forums, the AF is tightening their ROTC scholarship belt, and due to the economy it has become incredibly competitive. I wold say for AFROTC if your gpa is unweighted, and you have taken all Honors/AP/IB classes, with a 1300 SAT (out of 1600) you should qualify for a type 2 or 7. If you want type 1, (the full ride to anywhere) you need to ratchet it up a couple of notches. Look for at least a 3.7 uwgpa and 1450+ marker.