What's the Difference?
VGA monitors have been a standard since computers began to take off. VGA, which stands for video graphics array, is an invention for use with CRT monitors; you know, the big computer monitor you're replacing with the flat screens? Video signals that come from your video card are actually in a digital format and then are turned into an analog format when going through the VGA port. Think of the VGA port as your home television set without cable. VGA connections are recognized by their blue connection color.
DVI, which stands for digital video interface, is the next in the line of visualization. With LCD monitors coming out and becoming popular, the use of DVI allows for the digital format of the video card to continue the quality of a digital picture. Unfortunately, this new standard took a while to be implemented, as most video cards and monitors were still using the VGA format. Think of DVI as having cable or digital cable on your home television. DVI connections are usually white or black in color (white on the card, black or white with an adapter or cord)
The good news about this is the fact that video cards now either come with both a VGA or DVI port, which you can use for either one or for the use of two monitors, or they come with a DVI and HDMI port. There is no need to worry if you're still using a VGA monitor; as mentioned above, the simplest and easiest solution is to stop and buy either an adapter. VGA to DVI adapters come in several forms; either two male ends or two female ends or a male end and female end; these are of course dependent on what type of connection your monitor and video card have. There are also DVI to VGA adapters in case you have a DVI monitor going to a VGA video card.
Usually, one end connects to your monitor cord (the VGA end) and the other end is a DVI connection that goes to your video card. Be sure to screw both connections in securely in order to ensure they stay connected to each other. These adapters will either be in either black or white colors and usually cost about $7 to $12, depending if you order online or go to a local retailer.
Image content @ Wikipedia and Tiger Direct