The Apple Software Update server could not be found. Check your Internet settings and try again.

If you see the error message:

The Apple Software Update server could not be found. Check your Internet settings and try again.

Open Control Panel > Network and Sharing > Internet Options > Advanced > Security and uncheck "Do not save encrypted pages to disk", then OK the change.

For assistance with other issues updating Apple software on Windows see Troubleshooting issues with iTunes for Windows updates.