that's the missing link, Internet Connection Sharing on the computer with the usb modem connection.

Also, the blue cable may or may not work here. You need a crossover cable, but, most modern NICs will recognize the swapped tx/rx signals and correct for that. It sounds like it worked with your desktop. Crossover cables are usually orange, I think, but the color itself really doesn't mean anything. You need the crossover cable so that the cable itself will crossover the tx signal from computer A to be the rx signal on computer B and vice versa. If you have a switch or a router in between the computers, you don't need/use crossover cables. You only need one to connect computer-computer direct and only if the NICs don't auto-adjust for it. There's a name for that feature, but I forget what it is. Auto-sense maybe?

A wireless router with a built-in switch would be the better long term solution. They are so cheap these days, maybe $50 or less for a decent one.

-David