Tom,
Welcome to the forum!
To be honest, I never even knew NXG sold remotes. Based on the photos I found, it looks like the remote you are referring to is a rebranded MX-850 with a different paint job. The main difference between this remote and your 800 is the improved select button which is now separate from the cursor buttons. The new remote may also support Narrow Band RF base stations such as the MRF-350, but I can't say for certain. I'm sure someone here can enlighten us. :)
As far as getting the software for the NGX remote, I'm afraid I don't know what to tell you. Normally, you would go to URC's site, enter your serial number, and you could download the software directly from them. Unfortunately, I'm not sure how this works with rebranded products. Again, I'm certain others here know more about this than me (particularly Dale). Once you do get the software, it shouldn't be a problem uploading the configuration to your PC and then downloading it to the new remote. If memory serves me correctly, MX-800 files and MX-850 files are fully compatible.
You may also want to consider going with one of the newer generation of remotes. URC's MX-900 is quite popular, and it offers a lot of bang for the buck. :)
Last edited by Loraquest on February 26, 2009 23:03.