On Windows-based PCs, video performance plays a critical role in how fast the computer appears to operate. Even with a Pentium III processor, you may find yourself twiddling your thumbs if the system takes a long time to redraw images on the screen.

The key to video performance is the video card. The card determines the number of colors the monitor will display, as well as the resolution and the speed at which the images appear.

Most systems today come with cards that can handle eight-bit color, or 256 colors simultaneously on a screen. For users requiring more realistic images, many systems can be equipped with video cards offering 16-bit or 24-bit color. These can display 65,000 and 16.7 million colors, respectively.

To handle the enormous amount of data that comes with displaying so many colors, good video cards include specially-designed processors and memory (video RAM). Cards typically come equipped with 1 to 4 MB of video RAM. If you expect to use a large monitor or need to display many colors, however, look for a card with 4, 8 or even 16 MB of video RAM.