Well, the 2610 comes with FULL European mapping.
It also comes with Mapsource so you can do your route plannig onthe PC, unlike the Tom Tom.
Tom Tom charge more for European maps, ISTR.
You can get a 2610 for around £200 these days.
All you'll need to add is the bike mount (around £30) and the bits from RAM (also around £30).
You can get a 2GB CF card for under £40 which means you can dump ALL the maps onto the 2610 if you're happy route planning that way.
Oh, and it's waterproof.
And the mount works and doesn't bugger up the electrical connections unlike the Tom Tom mount.