Hi James,
Wiser heads than mine will correct me if I'm wrong but, from reading the forums, I think that, because of the small number of units sold there is less support for new software roms etc. for the 5600 than for any other Zaurus.
Therefore you may be better off buying a 5500 which, although older, was launched worldwide and as there are more of them better supported. It may even be a little bit cheaper. I think I remember seeing one mentioned on here recently for 140 usd.
Welcome and Enjoy,
Chas