Have you tried going to:
and adding the extra rpm sources? I believe there is an rpm for ndiswrapper in one of those places. Hehe, I guess that's kind of hard to do if you don't have internet.
It's one of the catch 22's of Linux I think. You need internet to set just about anything up... and a lot of time that includes the internet connection itself. Well, even if you had ndiswrapper, you'd still have to download the file from the driver for you wireless card... If you get access to another computer with internet, I believe this is the rpm you'll need.
It's the most up to date ndiswrapper rpm for mandrake that I saw. It might not be as stable as some of the older ones, but usually it's better to get newer releases for ndiswrapper because they are continually increasing compatibility.