How to set up dual monitors in XP

Hi, I've searched long and hard for info' on setting up dual monitors based on my Acer 530 laptop. I've found lots of stuff but nothing specific to my situation. So I hope someone may be able to help (and I hope this is the right forum).

I already have a Samsung 19in monitor hooked to my laptop (working fine) but the laptop screen is black (except on startup).

How can I tell if I can run dual monitors, or find out what I need if I can't?

I don't have DualView and when I look under Display/Settings it states "Multiple Monitors Intel(R) 82852/82855 GM/GME Graphics Controller".
There is only one monitor displayed and no tabs for options to extend this (as suggested in various places).

What do I do?

TIA,
Grahame