Go to Start/Search and type devmgmt.msc, right click the devmgmt results and Run As Administrator. In the Elevated Device Manager are there any devices with a yellow flag? If so, these devices need drivers installed.
Do you have a separate Video Card? or are you using the onboard VGA? What is the make and model of the Video card? Go to the manufacturer of the video card Support/Download Drivers and type in your make and model # and download the driver for your video card.