I have a setup similiar to yours. I use portmapper by analogx. It directs requests from several ports to any other ip that you choose. The only problem that I noticed is that my linux machine logs all incoming as 192.168.0.1 (the secondary nic from my win2000 computer).
I use mine for http and ssh connections.
portmapper
Does anyone know what we could use to get the correct ip address of all connections?