Most anything will work on a machine like that. I would steer clear of KDE though, it will be way too slow.

I have Slack-8 running on a 120Mhz Pent Laptop with 48 Megs of RAM. It is a little sluggish at some things like Mozilla (so I run Opera instead), but it is otherwise very usable. Installing it was a trick since Laptop doesn't have a CDROM. I think the first time I did it I installed the base packages from a parellel port zip drive booted from a floppy or something like that. The next time I just copied all the packages over to the hard drive through a net connection ahead of time.

I've tried Redhat and Slackware, and they are a bit slow on my P133/32mb/6.4gb machine. But linuxfromscratch.org told me how to create a fast system from source instead of binaries. My customized system compiles a default Linux kernel 32% faster than Slackware 9, and I know how the whole thing is put together, since I did it myself. Check it out.

Slack isn't too hard to install -- just print out the slackware install howto and go step by step....

You could probably go with Slack 9.1 and windowmaker/fluxbox.

Since slack 9.1 boots from CD, you don't have to worry about rawriting the boot/root disks.

The hardest part of the whole thing is using CFDISK, which is actually pretty easy.