I don't have experience with Tom Tom nor Distinator, but I have IGuidance installled on my Dell Axim x50v and Carputer. The Dell Axim is using a Belkin Bluetooth GPS receiver (works awsome) and the Carputer has a BU-303 USB GPS receiver connected. The software works pretty much the same between the two platforms. The advantage with the Dell Axim, IGuildance can read address directly from my contact list.
Only issue I have with IGuidance is the zoom buttons are too small and it's not as touch screen friendly as some of the other GPS software.