My 2400c w/240MHz G3 upgrade runs 10.2.6 with 112MB of RAM. It's pretty responsive, actually, though I've never tried running more than one program at once. iTunes plays fine (no visuals, at least not with more than 1 fps), Firefox works, iChat works. It's not the world's fastest machine, but aside from the lack of battery status monitoring and sleep abilities, it's completely usable.