|The term CARD is frequently mis-used.|
If the video adapter, or any device adapter, is built into the mboard and cannot be removed, IT'S NOT A CARD !
If your onboard (built into the mboard) video has both a VGA port and a DVI port, when I was looking at mboards about two years ago, I found that some mboards have a different type of DVI port, and that type WILL NOT work with a DVI (male - pins) to VGA (female - pin holes) gender adapter, or a DVI to VGA adapter video cable, to make a VGA connected monitor display !
If you have a generic system, if that applies, there is probably info about that in the manual for the mboard.
There is no such thing as a VGA (male - pins) to DVI (female - pin holes) gender adapter, or a VGA to DVI adapter cable, that will convert a VGA port on a video adapter to work with a DVI connected monitor - there are not enough connections in the VGA port for that to work.
In any case, Windows only enables one display by default (at least, that applies in XP and below).
RIGHT click on a blank part of your main desktop screen, select Personalize, then Display Settings.
Hold your cursor over the two displays, one at a time.
One will display Not Active.
RIGHT click on that display, and select Attached.
Click OK at the bottom of the Display Settings window. Close the Personalization window.
Windows will retain the second display as long as it is still connected while Windows is running, even after you Shut Down Windows.