Thanks for the info, I found a previous thread where you mentioned an SDIO card so I had a quick look on Ebay. Found a Spectec one but missed out on the auction so in an act of impatience I ordered an
The Ambeon Wireless SD Card, which I'm hoping is the same thing.
Tried the TomTom software out yesterday and it worked well, apart from not knowing where a few One Way roads had been put in. Even then it quickly figured an alternative route out for me. 
B.