I know as far as Nvidia is concerned all their cards from at least a year ago (maybe earlier) to present have this funtion built in. "Nview" is automatically an included feature of all detonator drivers, thus all cards support it.
The last time I saw an Nvida card that didn't support dual monitors was my old Gforce 2 from 3 years ago.

Glen wrote: <<Don't need a second video card to do dual monitors. Just connect the second monitor via the DVI or Analog port and configure it in Nview>>

OK, thanks for all details but what I'm missing is the physical connection of the monitors to the VGA slot. Where the first monitor connects?
Does the card have 2 connectors so you connect 2 monitors?
Otherwise I know most of the modern cards support this function.
Sorry for the ignorance.

Yes, modern Nvidia cards have two connections..one for analog (CRTs) and one DVI (for LCDs). I actually have two LCDs that, oddly enough, connect via an analog interface. Just plugged the first one into the analog port and the second into the DVI via a DVI to Analog adapter that was conveniently included with my videocard when I bought it. Once in windows right click go to Properties> Settings Tab> Advanced> Nview. Click the button that states "span desktop horizontally" and POOF your done. The newest Nvidia drivers auto detect the second monitor connected and automatically prompt you with a wizard to configure your second monitor.

Glen,
Thank you so much for the detailed explanation!