Actually,
I had an Amiga 1200 about 1 year ago. While it has a nice UI, AmigaOS still has a lot of quirks. I was running 3.1 with 20MB of RAM and a 2GB HD. I also had an 030/40 in it.
Nice OS, but not too suited to the modern world. I was happier with my 200Mhz Cyrix box running Red Hat 6.1 in 64MB RAM. While I liked amIRC and the web browsers, it just had a very weird UI. I like OSX's and Windows 2000's. XP I put in classic mode whenever I have to use it, since I can't stand the new UI.
However, it did its job in a small amount of RAM, and got most of its speedup from the fact that there was no memory protection whatsoever.
Now, I'm running a 1GHz P3 with 512MB RAM and a 40GB HD with Windows 2000 Professional. I may consider putting Linux on a second HD, but considering I have everytihng filled in there now that I have a 32X CDRW, and DVD-ROM, I may not. That, and Linux drivers for my hardware aren't the greatest, especially my ATI All In Wonder Radeon 7500.
Actually, I'm considering getting an AmigaOne, if and when they come out with AmigaOS 4.0. At least then the OS will be running on PPC then, and be a little faster

. That, and they'll have a lot of Linux apps ported over, since the new developers are using GCC.
Mitch