Hi Gareth -

I'd recommend the interface cable, though Garmin only offers the serial connector right now for your model. I understand there are one or two of the newest models that are USB. If you use one of the Mapsource software packages, you can either download whatever's in the GPS, upload maps and waypoints, or use the GPS realtime with a laptop in a car or motorhome. There's also some freeware out there that will do lots of the same stuff but without some of the glitzy features. I purchased the Mapsource to get the product support, which is considerable. I occasionally see people posting info from Mapsource on the forums (including this thread, thanks Gary). In the Worrell and Tybee races, we use Mapsource daily, and I have the last several campaigns on file - nice to look at when preparing for the next one, in addition to giving us some fixes on features to seek out (a safe cut through jetties at night) or avoid (Newkirk's Island).

Cheers -