Chuck, you may very well be right. I was making an assumption about 4.2 being .net from a note from wikipedia:
"CE v3.0 is the basis for Pocket PC 2002. A successor to CE v3.0 is CE.net"
http://en.wikipedia.org/wiki/Windows_CE
I don't think it matters as I researched things more and it appears many CE 4.2 apps will run on CE 5.0. Considering you got SYSRegister to work on your phone and PDA, I bet it will work fine on the V212.
PS: if you haven't looked at it yet, the V212-003 is an interesting device:
http://www.viewsonic.com/products/v212003.htm
I ordered one and will report back here with the results. Considering the V212 is native 800x600 (same as the AB) and may work with SYSRegister, it could be worth purchasing a few if you can find them cheap (less than $125)
The one thing that worries me is the batteries for the V212...where do you find them? Also, as you said earlier the AB may run slow on it, but I guess I'll find out in a week or so.