Here's how you can bring your computer up to date with the available security updates. You can also use these instructions to keep up with the latest non-critical updates.
Note: These are instructions for Windows XP. For Windows Vista and Windows 7 please open Start, then choose Windows Update.
1. Go to the Windows Update website at www.windowsupdate.com.
2. Click Express Install. Windows Update scans your computer and displays a pre-selected list of critical updates, including security updates and service packs:
3. Click Install... to begin the download and installation.
4. Note: Slower computers might take several hours to download all recommended updates the first time you use Windows Update. Download times might vary depending on computer and network speed and how many updates your computer needs. To reduce download times, run Windows Update downloads when you are not using your computer for other Internet-related tasks.
5. Click I Accept at the End User License Agreement.
6. The updates will now download. Download times depend on size of the update, number of updates and connection speed.
7. Most updates will require you to restart your computer. When or if it does prompt you please restart your computer. Click on the 
icon at the bottom right corner of your screen, select login and enter your credentials. The system will tell you if you have more updates to install.
Windows® XP has an Automatic Updates feature that you can use to download the latest security updates automatically on a schedule you choose.
Turn on the Automatic Updates feature
1. Click Start, and then click Control Panel.
2. Click Performance and Maintenance.
Note: If the Performance and Maintenance category is not visible, click Switch to Category View in the left pane.
3. Click System.
4. Click Automatic Updates and then select Keep my computer up to date.
5. Select a setting. Microsoft recommends selecting "Automatically download the updates, and install them on the schedule that I specify and setting a daily update."
Important: You can set the automatic download time for any time, day or night. Just be sure your computer is on at that time. (We recommend a time when you will not be using the computer, but it will have to be turned on.)