is it possible (Ubuntu and Windows) to create the following rules:
If target="192.168.*" use eth0
If target="*" use eht1 // default, the rest that doesn't match another rule
Read up on subnetting and the route command. It is designed for this. Specifically, use the route add command.
That is done by putting the default gateway via eth1.
This is basic TCP/IP networking, and is the same on both windows and GNU/Linux.