All the little graphical flourishes in Windows XP help make it more fun to use, but they also make the CPU (central processing unit) and video card work harder. For example, have you ever noticed how when you open a menu, it doesn't just appear -- it sort of fades in? Or how when you move the mouse across the desktop, it looks like it has a faint shadow behind it? Those extra niceties aren't free -- they cost you in terms of memory usage.

So let's say you want to have the leanest, meanest computer possible, eliminating every unnecessary extra that could slow it down. In the following sections, you find out which Windows settings can make that happen for you.

Display performance is the display's ability to keep up with the commands it gets from the operating system. For example, have you ever seen the screen "paint" itself, from top to bottom, a few strips at a time? Or has a video clip in a game or other application ever been choppy? These are examples of poor display performance.

Resolution and Color Depth

The resolution is the number of pixels that make up the display. The more pixels or dpi (dots per inch), the finer the level of detail, and the smaller everything appears on-screen. For example, at a high resolution such as 1280 x 1024, all of the icons on the desktop appear very tiny, whereas at a low resolution such as 800 x 600, they appear much larger. The reason is that an icon, a menu, a character of text, and so on is a precise number of pixels in size. When the pixels are smaller and closer together, the object looks smaller. The Windows desktop, on the other hand, always expands to fill the entire available screen space; it doesn't have a fixed size.

High-resolution display modes may be enjoyable to use, but if you have an old or cheap video card, your computer may not run as well in a high-resolution display mode as in a lower mode. For an old, slow computer, switching to 800 x 600 can provide a small performance boost. (You probably won't notice a difference on a new, faster computer.)

In earlier versions of Windows, the lowest resolution was 640 x 480, but in Windows XP, the lowest resolution is 800 x 600.

Color depth is the number of colors to select from for each pixel. The higher the color depth, the more unique colors you can display at once on-screen, and thus the better your photographs and graphics will look. Color depth is measured in bits. For example, 4-bit color depth provides 16-color choices because 16 combinations are possible with a 4-digit binary number (2 to the 4th power). The Windows XP default is 32-bit color, which results in a very good quality display.

On an old, slow computer, you may be able to get slightly better video performance if you decrease the color depth to a Medium setting (16-bit or 24-bit) instead of the default 32-bit.

To adjust the resolution and color depth, right-click the desktop and select Properties, click the Settings tab, shown in Figure 5-5, and then change the resolution and color quality settings. Click OK.

Figure 5-5: Display Properties Settings tab.

If this is the first time you've selected that particular resolution or color depth, a dialog box appears asking you to confirm whether the new mode works. Click Yes within 15 seconds or the display will revert to the previous settings.