BasicLinux

This distro features a very small kernel with most drivers as optional loadable modules. It will run on a 386 or better with 3 megs of RAM. Includes a special minimal Xserver called Xvesa and uses busybox to minimize the footprint of the standard UNIX utilities.

You can find more info and downloads here: http://distro.ibiblio.org/pub/linux/distributions/baslinux/