Email on the move

[Ray]

Hi there,

My laptop has Ubuntu 10.10 on it and I want to be able to use it when we are
away in the caravan without mains power. 
Yesterday I purchased  a small inverter that runs off the 12 volts from the
4x4 and this seems to fire up the laptop OK.
Now, to get email etc I guess I need to buy a USB modem.
The ones I looked at yesterday say for Windows or Mac - will these generally
be OK for Linux too, or do I need a special one?
The shop assistant just rolled their eyes and said, dunno !
TIA.

Ned