Windows Update Service is a great tool to manage and distribute patches from Microsoft with your organization.
There is a GUI based way to do it. But there is a great tool available from the CodePlex website http://wsus.codeplex.com/releases/view/17612 to run it as a regular maintenance scheduled task.
It will save you disk space and can also remove orphaned computer entries.
Microsoft has a patch day once a month on the second Tuesday. Some patches will come during the month too.
So please sync first your WSUS with Microsoft and run e.g. once a month the WSUS Cleanup tool.