Hmm, does your Plasma have a DVI Socket? They're the sockets similar (if not identical) to the one on the back of your laptop, same as the monitor via to your computer. Anyway, you need one of them, i don't know what the wires called, i assume its called a DVI cable because thats what it is. I think you can get them from most PC stores or Maplin or Comet? I got mine with my Evesham LCD television (good lcd by the way, cheap as cheaps, £649.99 for 32" HD Ready and PC quality is top).
(Also you'll need another method to transmit the sound from the laptop, since the vga cables, plugs and sockets are for your laptops monitor only.)