I took a look at the Landrider site (
http://www.landrider.com), and see a couple of issues that that bike presents. If yours is like the ones pictured there it has a suspension fork up front, and that's generally not a good idea with a motorized front wheel. But if you like the Auto-Shift feature, that may not work with a rear wheel kit (at least not without a lot of work.)
The easiest way around this would be to replace the front fork with a steel non-suspension unit and get a front wheel kit for it. Not sure how much a fork would cost, but a local bike shop should be able to help you out with sourcing one and installing it. You'll also need to switch from disk brake to standard brakes on the front as the hub isn't fitted for the disk.
As for the rear wheel kit, I'd recommend against it, even if the Auto-Shift thing isn't an issue for you. I just bought a rear wheel kit and won't get mine on a bike for some time, after some machine shop work and getting the wheel dished. It's definitely not ready for prime time.