I'm lovin' my 2007 HCH w/Nav, and was utterly surprised by the XM radio included. Guys at the dealership are still a little flummoxed by the operation of the XM, however. By trial and error, I finally determiined that the little symbols that look like little barbells actually mean that you can switch from category to category by pressing and holding the the channel rocker switch. But I still can't figure out the difference between "Channel Mode" and "Category Mode" since everything seems to work the same way in either mode, and the dealership wonks are no help.

Can anyone enlighten me about the two modes?

By the way, if anyone's tempted to install the MusicLink, hold off. They're in the process of upgrading the hardware, and the software probably won't be updated for another couple of months.

Oh, and accessories aside, with the help of this forum the mileage is starting to look pretty good, too.

XM radio is set up so that similar stations are grouped together in Categories (so "Decades" includes channels from 4-9; Country from 10-17; Hits from 20-30; Christian from 32-34, etc.). See, e.g., http://www.xmradio.com/onxm/full-channel-listing.xmc .

When you press & hold the rocker switch until you hear a beep, you switch to the first station of the next Category. When you simple press but don't hold the rocker switch you go to the next station (whether or not it is in that same category).