i use Debian Sarge 3.1R1 (latest stable) on a P1@100Mhz with 74M ram and 6Ghdd, and same Laptop has Slackware10.2 (latest stable release)installed.
both work great on it (i use icwwm as KDE and GNOME are too heavy).
it is no performer but it is ok to surf and do mail...