hi,
--AUTSCH-- 8o
that is basically the only thing I can say.
winxp does not have something like a router included in its system package so you can't tell windows to route the 3 ports you need to a specific 2nd computer.
if you want to leave it like that only thing you could to is to get a routing software like
winroute for windows. it is pretty good configurable and will mangage what you need.
if you can't get that software, just switching the order of the pc would help aswell.
let the linux connect to the internet and share its connection. much easier and here port forwarding works

stefanero