Just my opinion, but
FreeBSD with a light windows manager like Fluxbox might outperform Linux on that meager box. I have run FreeBSD on a Celeron 400 with 32MB RAM, 3 gig HD, 100MB network card, Sound blaster compat SC, AGP1X 8Meg video integrated, and it is a usable box. Not lightening but usable. BSD doesn't have the stalling problem on a network that Linux has.
Light applications like Sylpheed for an e-mail client, nedit for editor, xterm, aterm for shells, Xcalc, Rox for a file mgr, XCD player, File Roller for archiving, XnView image viewer, Xpdf etc. and you can make that old machine work usably with X and a windows mgr with most Linux distros.
Lots of distro choices, just stay light on the WMs and apps. I see that DSL has Dillo. Thats a great fast little browser but it doesn't render pages correctly. Firefox won't run real fast on a P133 type.
Good luck, I like to put those old machines back into service too.