Can I swap NAV head unit for factory XM?

I'm thinking the answer is probably "NO" but thought I'd ask. I have the factory NAV head unit in my 2006 and, as neat-o as it is...I like the functionality and especially the aux. input on the standard XM unit much better in my '07! Is there a way to swap these without doing any T-2 programming? Why on earth did they not include an aux input in the much more expensive NAV unit for crap sakes?!!

Thx :)