Unless the computer in question is well and fully borked, you would probably have best luck with a software based multiheading solution. Under Linux this should be a (fairly) simple matter of playing with network and X configurations (n.b. I speak as a man who has never had to do it). Under Windows, hit
http://www.maxivista.com. I have not used this product myself, but I've seen complimentary references to it here and there. Neither of these will do really hardcore full motion video or anything; but many dual head cards won't do that for a directly connected screen anyway, so that is no great loss. It will still be fine for a page of text, or your photoshop toolbars, etc.
Again, either of these options requires that the laptop be operational and may require that you buy a cardbus eithernet card or something, but if these conditions are met doing the job in software will make your life
much easier.