There's not really a very good way to make that work. You could manually add a second default route for the second connection, and it might work, but, then again, it might not. It depends largely on the OS. But, at best, you'll be sending requests for half of your things out of one interface and requests for the other half out of the other interface, and receiving the replies for each thing back on the interface you sent them from. Without using relatively advanced networking protocols (which wouldn't actually work for you because standard internet policies would tend to prevent it working for such a small network), there's no way to really combine them.