Thanks to all your help I'm now an "expert" at installing pfSense 2.1.
In short, I can get a good basic working system.
I did get several hangs on reboot while trying to set up a WLAN. Now I've got about 10 config backups after taking wallabybob's advice and quite a few of them have been used. Had to reimage a few times I got so stuck. But now I'm on a good config and it all seems good.
I followed this method to set a WLAN on my Atheros AR9280. Config looks like this:
I could also "sort of" get it working in 802.11ng mode, except when I do it reverts to channel 1 (no matter what I set it to in the webGUI) and I run out of patience waiting for my Windows box to connect again. That is, pfSense boots fine and I can mess around on its shell and ifconfig tells me that the WLAN is in 802.11ng mode, but I can't connect via the LAN with my Windows box (and I didn't try with a wifi device). Rebooted pfSense, Windows, reconnected cables, after about 10 minutes of stuffing around I gave up. So I'll stick with 802.11g for now (good enough for my needs) and revisit the topic later on.
802.11n isn't an option on the drop-down box in the webGUI, just ng (amongst others).
I added these lines to loader.conf.local, not sure if I need them:
I'm happy to post any specifics if you want to know more about my config.
Thanks again.