what you suggest would probably work. If you're running a later version of Windows, Windows Internet Connection Sharing will work well for what you want to do.
If you're only going to be connecting 1 other computer, I'd probably forget the hub, and just use an ethernet crossover cable from your (new) 2nd NIC to his computer.
(Probably easier to buy a pre-made crossover cable, but if you're the type of person who likes to roll their own, pinout is
1-3
2-6
3-1
6-2
(regular ethernet cable is 1-1, 2-2, 3-3, 6-6))