Got a friend with a Dell computer to which he wants to add a second monitor. He currently has 1 onboard VGA.

He wants to add another 15" TFT the same as the one he has now (Dell branded). Whats the best way to connect 2xVGA monitor?

New graphics card with 2xVGA ports?
New graphics card with one VGA and another diffrent port?
New graphics card with the same as the onboard chipset and one VGA port?

Will two identicle monitors, one on VGA and the other on S-video or DVI look identicle?

Not too sure  .....

new card with 2xVGA Outputs.  The onboard Intel graphics normally cuts out when you add a card in, but a decent card with 1xVGA and 1xDVI would be fine, there is normally a DVI>VGA Adaptor in the box, and if not they are only a couple of quid.