Here's a guide which learns you how to remove spyware and viruses and optimize your Windows XP system to improve performance.
Clean Spyware and Viruses + Optimize Windows XP to improve home, work and gaming performance safely. Windows XP's default configuration is far from optimized. This Free guide will help you improve your overall system performance without having to manually edit the Registry. I avoid using or recommending "all-in-one" Windows XP Tweak programs since many blindly adjust settings that have no affect on performance and can cause future problems. This guide is designed to be performed top to bottom, in sequence since some steps are required to be performed before others.You can check out the full guide over here.