I decided to give Gnome a run through on my desktop. The version in the Arch repos is 2.22 as of writing this. I hadn't used gnome since my Ubuntu days, and I must say I am pleasantly surprised by Gnome. While it's not Openbox, it's still fairly responsive on my hardware (which is, admittedly, fairly up to date). I also installed firefox3 from the Arch repos, and let me tell you the hype about a smaller memory footprint is true.
I may see if this runs OK on my mother's computer which only has 192 Megs of memory. I mostly don't want to bother torturing them with the whole right click + no desktop icons only because I know it'll become annoying to explain over and over again.
I'll probably end up doing something similar to my father's computer; He's still running under Ubuntu and it'd just make the transition WAY easier.