Some graphics options are unnecessary
By toning down some of the fancy display options (shadows, textures, highlights), you can speed up system performance. As with many other speed tweaks, how much it helps, varies.
Click Start->control panel->system settings->advanced->settings
Simply Select 'Adjust for best performance'
Windows Vista and Windows 7
Click Start->Control Panel->Appearance and Personalization->Personalization
Choose Windows Classic theme
Tip: Using a plain solid color desktop may improve performance.