Hey Larry - I have the Zumo 550 and as stated above, don't have a need for the external antenna, and I don't think it has a port for one. The XM IS built in but requires a $200 antenna which does have a port built in.
The bluetooth is totally optional and you can run wired sound for both the car and bike. The car does have a speaker in the mount which is fine for voice prompts, but you can do the cheapo cassette adapter if you want stereo thru the car speakers, or get a wireless FM adapter for an ipod and they work also.
The problem with bluetooth on the bike is they don't support stereo (yet) so I'll wait awhile on that. I use these
cheapo earplug headphones and they work great for roadtrips.
Never used the TomTom, but all the reveiws at the time were going for the Zumo. It's a bit spendy, but pretty much comes with everything you need.....
Jeff
