Sometimes I use Breadbox Ensemble (technically a "DOS Shell"). I don't know if that's what you're really looking for though, since it's basically a more user friendly version of Windows 95/3.1. If you're interested, though, you can download the demo from www.ftp.breadbox.com
I've been using shell replacements for a really long time now ... been using them from old Win98 days...
There are lots of shells available these days ... to name a few Litestep,Darkstep,Aston shell,DesktopX,Talisman etc..
Personally i prefer Litestep..... It has a very small footprint,will run on most systems,very very customisable n' has tons of modules available for it.
You can have a look at my curent desktop which i've built on Litestep itself , it's based on a theme from Talisman. If you have any more queries on this post em'!