When I boot up my Windows XP computer, I keep getting a pop-up above my system tray that says: Updates are ready for your computer. Click here to install these updates. How do I know this is not some kind of virus? There is no indication who is sending them.
You’re wise to be cautious. I assume you’re running antivirus software and that it’s kept current. But to respond to your question: If the pop-up balloon is directly over a small yellow shield icon in the taskbar, then it’s coming from Microsoft, and it’s safe. If you right-click on the shield icon, it will tell you how many updates it has for you to install.
That screen will also give you options on how to install them. Click on Express and Windows will do the installation straightaway. If you click on Custom Install, you’ll get a list with the name of each update and what it’s designed to do plus the further option of either installing each one or skipping the installation.
You can adjust future settings by going to Start, Control Panel, Security Center (see screenshot below).
If you click on Change the way Security Center alerts me…
…you’ll get this choice: