I've also just found another lightweight Linux distro called Puppy Linux.

http://www.puppylinux.org/

This one is meant to only need 32MB of ram to work perfectly and is designed for really old hardware such as P1 systems. It can also run from a USB memory stick, or from CD. I might give this a go from a memory stick just to see how good it is. The download is only 88MB too.