Disabling Ctrl-Alt-Fn. Would be a very good idea.

I built a kiosk station from Suse Linux. Here are a few steps I took:
Disable Ctrl-Alt-FN. (I left one open, just in case)
Set Grub boot menu to load in 0 seconds.
I disabled Ctrl-Alt-Del. You could disable Ctrl-Alt-Backspace. I left
mine on just in case the GUI got locked. But since these distro's boot off
the CD then you don't really care about the FileSystem so disabling
Ctrl-Alt-BkSp would be ok. Then they would just need to reboot the
kiosk. I also locked down firefox as tight as I can. No right clicks,
no printing, they can't change anything except the address in the address
bar. Even then we don't let them browse off campus.
I set this up about 6 months ago and I was searching high/low for a bootable,
cd kiosk. Since I didn't find one I decided to build my own. The down side is that
I lost one of the partitions once when the power went out. If it was a cd I wouldn't have had that problem. But, (one more thing i'm doing) I tarred up the
home directory when I was finished. so on each reboot I delete the homedir and
recreate it. This just keeps things clean.
BB