Rob:
Raul has some very interesting choices. I'll second the Yoper comments. I tried it on my old PIII 450 laptop that's stuck at 64M of RAM and it ran surprisingly well.
If you want a Linux distro that's mostly source-based like BSD, try Crux. It's very quick, though the default window manager is WindowMaker, so that'll always seem faster than KDE, which is what Yoper runs as default. But you have the same ports-like, build-from-sources system without having to start from scratch like Gentoo. And there's Slackware, of course. That's my favorite distro. It's supposed to be the most Unix-like.
As for ones I'd like to try, I've always wanted to try one of those Be-like OSes. They seem different enough from Linux/BSD to be interesting.
Have fun,
joe f.
