A crucial part of having a secure and stable computer is keeping Windows updated. Luckily with Windows XP it's quite easy to keep everything running smoothly.
First off, you will need to use Internet Explorer since the Windows update makes extensive use of Microsoft's ActiveX technology. Open of Internet Explorer and enter http://update.microsoft.com. You will be redirected based on your version of Windows.
You should see a screen like this one if you have everything set up properly.

*If you receive messages telling you that you need to update your software, follow the instructions.
The easiest thing to do now is to click Express and let Microsoft choose what updates to install based on how critical the updates are.
Windows Update will now scan your computer and decide what updates are most important. You will then see a screen like the one below. Click Details to see which updates are to be included to see what will be changed.
Now click Download and Install Now and your on your way.
If in the future you wish to have Windows automatically update your computer, click Enable Automatic Updates at the first screen. Choose the times for installation that best fit your schedule and that wont affect your day to day use.
Windows Update is a critical component of a secure and stable computer. Keeping your computer updated can help you avoid many of the exploits which many of the talking heads talk about on the evening news. It's a easy way to secure your computer, just do it.