Here is a detailed description of how to do this with fedora core 5. Since it is free and the most recent red hat/fedora offering (should be pretty stable, fc 6 is set to come out soon), why don't you pursue this avenue for a less muss and fuss solution?
Hope this helps.
Here is another detailed help page
If you wish to keep using Red Hat, here is a page describing a commercial product with free 30 day trial which allows you to use the windows binary driver in linux (supposedly ndiswrapper works just fine also, but there is no step-by-step description of commands).
Here are step-by-step instructions for ubuntu (note, according to this site, the D600 has two variants in its wireless card, and one of them is automatically supported by ubuntu).
Here are step-by-step instructions for both Debian Sarge and Red Hat 9 (note, this seems very detailed and comes at it from several angles, including customized Red Hat 9 kernels which may solve your problem)
This page indicates that Dell's published driver DOES NOT WORK, and that you should instead use Intel's driver:
This page is a forum back-and-forth for Mepis, describing the commands to be used in configuring ndiswrapper. At one point, a poster mentions that it should work automatically with Mepis now: