PC Stats posted a beginners guide on the Windows XP Safe Mode

In this article, PCstats will explain how Windows XP's various 'Safe Modes' work, how you access them and how they can help you troubleshoot various software and operating system issues. Now, isn't this a handy topic!? Safe Mode has been a component of the Windows operating system since the days of Windows 95. The basic idea is to allow the user (or technical support worker) access to the windows interface without loading any unnecessary drivers or software.

Windows XP Safe Mode Explained