|Good link modify.hardware.............if he was talking about dialup modems.|
There are a couple of issues which make it so you can't do this.
First, there's the fact that you want to try to utilize two different interfaces at the same time. Your operating system isn't designed to do this and doesn't have the necessary software to make it happen. Essentially what you're talking about is 'load balancing' between two NIC's. Windows Server operating systems have this capability, but not the desktop versions. But, even if you bought Windows Server 2008 you still couldn't do this because of issue number 2 below.
The second issue is you have two completely different connection types. You have a highspeed connect and a 3g wifi card. These are two completely different types of devices. One utilizes a network interface (NIC) and the other is a card you slip into a PCMCIA slot. 3g wifi cards were not ever intended to be used in this fashion and the software isn't capable of using it in this fashion.
If you had two broadband connections at home you could by a "dual WAN router" and that has the load balancing capability I discussed earlier and could utlilize two separate broadband connections. But I don't believe you'll find anything anywhere that could load balance with a 3g wifi card and any other connection type.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.