I've been using this
Windows Explorer replacement
shell on my
Windows 98 Second Edition box for about a
week now, and I'm amazed at its
robustness. It hasn't crashed once in the past
week, and my computer has been up the whole time.
It's quite too bad that they seemed to have ceased development of the product, and I can't find any themes, so I may make my own. Right now, my PC looks a little like a Mac, which is really cool for me, I can dig it, it even comes with a Unix-like theme. Some of the animations are more complex than they need be, but eye candy never hurt anyone on a fast enough machine (I got a celeron 300, FWIW, and I've noticed little/no problems with the animations/alpha blending/etc.).
It's easier to configure and maintain and set up than LiteStep. The coolest feature is the shell selection menu, which means you can select any different shell you want, it comes defaulted to Outsider and Explorer, but you can add any other one you feel like.
I reckon I recommend to try it out, if you don't mind futzing with some configuration just a tad. The home page is http://www.dtop.org/outsider99/