link mint is good, so I have heard.
I use Ubuntu.
The system RAM you have is going to be a problem for most distros. The processor too.
Xbuntu (XFCE desktop) is a lighter weight version of ubuntu (gnome)
and even Xbuntu requires 256MB of RAM, (even a 500Mhz CPU is really pushing it for speed, it would be slow) you could use a command line version without a graphical environment but that would defeat the purpose and still might not work well.
even the older versions referenced below, either you don't have enough hard drive or your don't have enough RAM. I am fairly sure v6.06 LTS is no longer supported.
What you can install is something like DSL http://damnsmalllinux.org/
you can run that off a USB drive too, however this laptop doesn't have one.
they are a couple of others, they don't have the large range of hardware support like popular distros like Ubuntu has. So you might have some hard ware problems, sound or something.
Most people with a laptop of this age and specs run some kind of server distro, since thats about what it will do. (simple FTP/HTTP server, maybe even a SIP server with some kind of VOIP gateway device).
My computer is using about 800MB of RAM with the different apps I have running right now.