Garmin are just as, if not more, reliable than Tom Toms, Tom Tom were on watchdog a few weeks back
they are basically just the hoover of the sat nav market, they got in first with all the advertising etc and now everyone just asks for tom tom
Garmin have been doing GPS systems for years, before tom tom was even thought of, mountain climbers etc dont use a tom tom, they use garmin, big tanker ships dont use tom tom, they use garmin, aeroplanes dont use tom tom, they use garmin, they know the most about the whole system and they are very reliable with excellent customer support
im sure tom toms are perfectly fine and more than likely very good, but dont overlook any of the garmin units as they are excellent sat navs and im sure in a year or 2 will be just as well known as tom tom