[Sharky]

OK thanks for the help.

After some extensive searching I have found a company that produce a transmitter that sends info from a cars diagnostic port to a PDA using Bluetooth, and so eradicates the need for cables at all (which I had found out about it earlier).

Waiting for some prices from the manufacturer, but hopefully this will solve the problem and I will be able to use my iPAQ for system monitoring/diagnostic and data logging after all, and won't need to buy a laptop