You need to make sure that you installed the package for your kernel source first. If you look in /usr/src you should see a folder called linux-2.6.3-7mdk if your sources are installed (your numbers may be different depending on your kernel version). Then go to this link
http://www.mattfoster.clara.co.uk/madwifi-3.htm
and run the commands under section 3.3.
Now the discouraging part. I compiled my madwifi drivers correctly and the modules are loaded properly. I just don't know how to make the association between those modules and my card. When I try to configure my card they aren't in the list of available drivers. Does anyone know how to fix this?