IMO none of the non-root methods are 1/10th as good as TiBackUp. What is the reason you're not going to root? Seems as though you came from a background of rooting, did you have a bad experience? Maybe a voided warranty screwed you out of a replacement device?
Far be it from me to talk you out of doing what you intend to do, but rooting (and unrooting) the DX is exceptionally easy. Simply download Z4Root from the market for free, press the root button, and you're golden. Need to unroot? Same process. It's sooo easy, a caveman could do it.
I'm only mentioning this because I don't like any of the non-rooted back-up methods myself. They really have to do something about that IMO. Until then, TiBackUp is a must as far as I'm concerned.
Welcome, and enjoy your new toy.