DSL a.k.a. Damn Small Linux
This is a very good Operating System. It a Linux distrobution made mainly by John Andrews, Robert Shingledecker, and Robert Lindsay. There are other members, but you can check this out @ damnsmalllinux.org. DSL is a very versatile 50MB mini desktop oriented Linux distribution.
Damn Small is small enough and smart enough to do the following things:
* Boot from a business card CD as a live linux distribution (LiveCD)
* Boot from a USB pen drive
* Boot from within a host operating system (that's right, it can run *inside* Windows)
* Run very nicely from an IDE Compact Flash drive via a method we call "frugal install"