I want to create and ad hoc network between a Windows 7 desktop (w/o an internet connection) and a Linux Mint 10 laptop (w/ an internet connection)
This is not difficult, and is a fun project.
I searched on share internet connection iptables and found this HOWTO
(there are lots of others).
It says "Only for ubuntu 7.10", but it should work for the newer versions as well.