What would you recommend for this specific hardware for a firewall box:

2xP1 200mhz MMX CPUs
256meg RAM
16x CD ROM
4 meg ATI Rage video card
and last (and least): 400Meg hard drive

I'd give smoothwall a shot but it wants 2 gigs of hard drive space, so I'm looking for something that will either fit on 400 megs, or run from a live-boot cd or a mix of both. I'm looking to put together a firewall box from this list of parts without making any investment in new hardware. I'm not looking for anything that will play games or let me do any word processing, all it has to do is just sit there and protect without a lot of monitoring (there will only be a monitor hooked up to it during boot and maintainance times, otherwise it will have none)

pfSense and m0n0wall are both FreeBSD-based firewall distros that can be run off the CD. The pfSense image is about 4MB which is pretty impressive, they aren't linux but should do what you're after

DSL, Puppy, Feather, Debian or Slackware + a light window manager.