View source for Windows Update for Windows 7

There are two things you want to do, first make sure that your machine is up-to-date, and then setup the automatic scheduling of updates.

To make sure that your machine is up-to-date:

Click:

Start --> Control Panel --> System and Security --> Windows Update --> Check for updates

There are two types of updates, important (security related) and other types.  We are mostly concerned with computer security, and these updates will always be considered "important".  If there are any "important" updates, click 

X important updates are available