I bought the version with the bundled GPS receiver. I figure I got a 1hz receiver for just $20, and I can transfer the software to any PC I want. I bought mine off Amazon.com.
I have the GPS receiver velcored to the interior of my dash (under the plastic) just above the main gauge console. I get at least 9 satellites and an accuracy of <50ft most of the time.
machine w/ the software only version. If you wish to change, then you have to deregister. The bundled will allow you to install on any computer, as long as u use the supplied receiver. So there are trade-offs.
Garmin Mobile PC, the software-only version, does.
The Garmin Mobile PC versions that come bundled with GPS20x or GPS10x will only refresh at 1Hz, because that's how the included GPS units refresh.
However, if you buy just the GMPC software, and use it in conjunction of a GPS receiver that refreshes at a higher than 1Hz rate, than you will see smoother map movement. I've tested it with a 5Hz receiver.
Garmin Mobile PC