i use backtrack to check my network settings and a few other things. as an installed os, i don't know as i only use the live cd.
if you want to install those programs, then as i always praise, Arch Linux is a suitable os. It's very lightweight, easy to setup, and i use it as a headless server. by default, the install is very small, and only install's the basics (things that are very important to have a linux install running). there's no xorg server, no desktop managers, just the bare bones basics. It's great on old systems, since it's so light, but can be made into a powerhouse.
i've used it on an old p2 system w/ 126mb ram and it ran just as fast (with openbox running that is).