Jeremy Schoen:I asked my school MSDNAA administrator but he doesn't know about XNA...
If your MSDNAA administrator took the extra steps to set up ELMS (e-academy License Management System) for your institution, then you normally have a place to go get your downloads+serial numbers by yourself. In that same place, you have access to an XNA Trial Subscription.
If you don't have ELMS, then you'll have to talk to your administrator, and tell him to investigate (either look carefully in his list of licenses, or check further with his Microsoft contact)