i'd also be interested to know about this, been looking at the new TomToms 300,500 and 700 but unsure of any others out there.
I think with the higher spec tomtoms you can integrate your bluetooth phone with it to accept calls etc but tbh that doesn't interest me all that much so the 300 would probably do me
I see there are also Garmin, Navman and Mio but dont know anyone who has these?