You should manually update your system to the latest service pack before you configure automatic updates. Go to Windows Update and install all service packs and critical updates.
Figure 1. Windows 7 Automatic Updates
Note: You should install Service Pack 3 on your system to obtain the latest automatic updates software.
Figure 1. Windows XP Automatic Updates
For more information on configuring automatic updates in Windows XP:
HOW TO: Configure and Use Automatic Updates in Windows XPSee the following Microsoft KB article:
HOW TO: Configure Automatic Upates by Registry Settings