How can you tell if your Windows PC is fully updated?

Windows 10
Press the Windows  +S key combination to display the “Search” box, then type windows update. Click Check for updates. Click the Check for updates button

Windows 7

Click here for instruction on how to find which version of Microsoft Windows you have.

Your computer checks for updates overnight every week and often will have to reboot. If you'd like to check for updates yourself (a good idea if you have a laptop), follow these directions:

Your Windows PC is up to date when you've installed the latest updates for Windows and your programs. To check for Windows updates, follow these steps:

1. Open Windows Update by clicking the Start button . Click on All Programs, and scroll and click on Windows Update.
2. In the left pane, click Check for updates, and then wait while Windows looks for the latest updates for your computer.
   
3. If any updates are found, click Install updates.
   
4. You might see both important and optional updates. Click install updates, click OK.
   -Note: You might be prompted to enter your administrator credentials, installing updates requires elevated administrator privileges.
5. Once updates are fully downloaded and installed a pop-up on the bottom left of your desktop screen might appear requesting a restart. 
   
   You have the option to delay restart though we encourage you to restart your computer immediately.
   Please remember to save all your data prior to restarting.