you can do it, I don't know why none of you have heard of this. With this program, you don't actually hook up your laptop monitor to your other computer, but rather you link them over the network. Then, the laptop monitor becomes an extended desktop of the main computer. The program is called MaxiVista(it has noting to do with MS Vista) and here is a free trial: MaxiVista - Download free trial
It works really well. I use it all the time with my old laptop that just has a wireless-b network card.