No worries g7nbp, thanks also to you for being the first person to get it started. I don't normally post stuff but it was because others like you took the time to write up their work that I could sort it out, so i figured I'd better return the favour.
I understand about your decision to stick with UNR. I also choose whichever suits my needs - for example my dedicated server is OpenBSD, my home server is Ubuntu 64, my main machine is OS X, and my MSI Wind is Debian. UNR didn't seem very far along when I last looked, I might take another look. For now the AA1 w/ Linpus just fits a particular need for me so I'm happy I could add Arduino. They are so cheap I think it was well worth it!
I would think Linpus would be ideal for an Arduino class - not many distractions and a simple interface. Although if you also intend to teach security then it could be hard work, but perhaps Backtrack would boot off an SD card in the AA1?