Hi,
If you haven't already, upgrade to 512 MB of RAM. Then, install DSL (Damn Small Linux), VecorLinux, or Debian
http://www.damnsmalllinux.org/
http://www.vectorlinux.com/
http://www.debian.org/
They will be lightest from DSL to Debian, with DSL being the lightest. The reason I mention the others is that DSL can be hard to install, it is done through the command line.