congratulations, Tulane ppl!
and yes, just write and say that you accept the offer. it's non-binding at this point. I just said something like "I am writing to accept the offer..." I may also have said "I'm so excited!" and used a bunch of exclamation points. so professional, lol....
I'm pretty set on moving to NOLA...I already have the NOLA weather report as an app on my iphone. I've become quite fond of informing my friends that it is usually 20 to 30 F warmer there than it is where we are right now