Excellent reply by Kanuti.
Let me add that for several years Toshiba has been "THE" laptop to consider first, having overall the best quality, and price/performance ratio. (This is highly debatable, of course.<g>)
Dell laptops have been improving in quality of late so they might not be a bad choice either.
Regarding Kanuti's article: options 3, and 4 are rather cumbersome, and it's not what you are looking for.
Option 2 works in every portable, so what I would do is to buy a portable with an external VGA port, (most laptops have it) and try to make the second monitor work. If it doesn't then I'd buy a PCMCIA video card, (They are not expensive) and that's guaranteed to work.
Good luck.
H.