Tip Control Windows XP Transition Effects for Menus and Windows gives you the info to control video effects. To get best performance, you disable the effects. If you hardware can handle it, enable ClearType font rendering.. Try it yourself but to my eyes, text is much sharper. To enable:

• Click Start
• Click Control Panel
• Click Display applet
• Click the Appearance tab
• Click the Effects box
• Click Use the following method to smooth edges of screen fonts:
• Select ClearType

You can use the following Microsoft link to fine tune Windows XP ClearType rendering for your monitor.