basically you want to use 2 network cards together to increase the speed. In other operating systems you can configure multiple network cards to share the load between them.
Unfortunately you can't make any *super* network cards from 2 connections and there is no way that i have found to enable load balancing in Windows.
The thing is, if you are physically hooked up and you have gigabit connection, there is no way anything you are doing is going to max it out.