Yes. Dial-up users can still receive critical Microsoft automatic updates. Microsoft's update service is set up to download any critical updates by trickling in large file updates in the background whenever you’re connected to the Internet by using any unused available bandwidth at any given moment.
If you disconnect in the middle of a download session, the update will pause where it left off and the download will resume the next time you establish an Internet connection. This process will continue for as long as it’s necessary until all the updates are downloaded. In order for the whole process to work, you have to set up Windows Update to download critical updates automatically.
To set up automatic updates, go to the Start Menu and select Control Panel. Click on the Performance and Maintenance icon, and then open the System control panel. Click the Automatic Updates tab and set Windows to download critical updates automatically.