Are all laptops true "dual screen"?

I have an application that drives two screens - the laptop LCD and the external VGA connection (in this case a projector). In this application, the two screens show quite different data, so I suspect that it is more than just an extended Windows desktop (or is that all it is?).
So my question is ... will any laptop with a 15-pin VGA connector do this, or will the cheapest only replicate the LCD data on the external port? If the cheapest won't do what I want, what 'feature' do I have to ask for to get this?

Thanks.

 

It shoud be fine. When I still had my M140, I drove its LCD (1280x800) & 2005FPW (1680x1050) at the same time no problem using VGA. All Windows does is recognize it as dual displays which can either be mirrored (you don't want that) or with one used as an extension (which you do want).

 

Exactly. If it has a video output at all, you can do it. It's common in offices to need this functionality, so even the cheapest laptops you find out there are able to do it.

 

Thanks, guys. I shall buy my cheap laptop with confidence now!