Windows Update: xp
It is critical that you keep Windows updated as much as possible. Since Windows is the most widely used OS (Operating System) in the world, it is also the biggest target for security issues.
Microsoft currently issues updates on the second Tuesday of each month. The updates that you need to be the most concerned with are the Critical Updates. Generally, though, I would go ahead and install all of the available updates.
As of Windows XP with Service Pack 2 (SP2), you have choices as to how your machine gets its updates.
To make sure about what version of Windows you are using, click Start. RIGHT-CLICK My Computer, then LEFT-CLICK Properties. You should see something like the following:
To make your choice as to how Windows Update will perform, click Start. RIGHT-CLICK My Computer, then LEFT-CLICK Properties. Select the Automatic Updates tab. You will get a dialog box like the one shown below:
The option selected above is the option that I would choose. Selecting Automatic Updates will allow Windows to download AND install the Critical Updates at the computer's first possible convenience. In other words, note that the update time selected is every day at 3:00 AM. This is a default time. If the computer is not on, it will check for updates when the computer is on AFTER that time. So if you turn on your computer at 10:00 AM, it will go out and look for updates.