Yes you can...
you can have two graphic cards ...or one graphics card having two connectors (the memory is shared between them )many graphics cards come with two ports now-a-days...
Here is how to do it...
Shutdown the computer, install the card, hook up the monitor to the new card and restart your computer. Windows will prompt you through installing the required drivers. Once you get the drivers installed you restart again. If everything is configured correctly, both monitors should come to life. First, your primary or master monitor will initialize with the memory test and loading as normal. The other monitor will display the following message.
"If you can read this message, Windows has successfully initialized this display adapter. To use this adapter as part of your Windows desktop, open the display option in the Control Panel and adjust the settings on the Settings tab."
If you see this message, congratulations, you've done everything right! (If it didn't work, don't give up! Try reinstalling the drivers. If you used the drivers provided by Windows... try the drivers that came with your new video card or visa-versa.
