I used Amithlon quite extensively several years before moving to AROS. It's pretty slick. I got it to work on several PIII machines from 800 MHz to 1 GHz. Got the video, audio, NIC and even USB working. My old Amiga Productivity Tools worked well, like ProWrite. And I was able to connect it to my home network which was cool. However, I gave up on it because at the time it had issues with P4 CPU's. Perhaps the new Kernal will fix that. Will have to try that.
I like AROS, because the install is very easy compared to Amithlon. Also, lately there has been a lot of development going on with it. Haiku hasn't had an update since May 10, 2010. AROS has several since that time. It also had multiple distributions, Icaros Desktop and Broadway. I've got it working on a Dell GX280 3.2 GHz HT CPU.
I have a spare Amithlon machine that I would like to give away to anyone who can pick it up. I'm in the Washington, DC area. It's dual boot with Windows XP. In XP mode, its a dog. But booting it into Amithlon, it flies. It's good for fooling around with.