My first sat nav was a TomTom 5.0 on PPC - and was very good, after I had Navman, Garmin 300T and now I have new TomTom 730T and ..... I don't like it. If you need proffesional sat nav - buy Garmin. TomTom have better user interface - more friendly (nice icons etc), but Garmin is more simple - that's why never crash. I think, after my return trip from europe I will have for sale TomTom 730T :)
BTW - I had also Harman Kardon - but I will never call it "sat nav".