Ian , I have had the co-pilot sat nav system on my t mobile pda for a year now, never a problem
it came free with a 1 year contract for the phone , it costs nothing extra per month . my monthy bill is £24 for that I get 300 free mins any time any network. the sat nav itself I have found actually on par with any of the dedicated sat nav systems in respect of direction, poi, etc etc.
the only drawback, that some may find annoying is . 1. typing your destination in takes a little longer. 2 the memory of all your destinations can soon fill storage space, however , providing you erase things you do not require on a regular basis . they are god.
one other advantage . you have a walk mode, very handy for been in a strange city... simply slip the sat reciever in your pocket, size of a lighter. and it will give you directions in yards.
Geoff.
ps it is programmed to work throughout Europe, and a disc allows you to install the programme for usa if your visiting there. So not bad really