Microsoft has a Windows Server Update Service (WSUS) utility that we can use to download updates and get them installed within the network. It can download updates for different versions Microsoft Windows Operating System. The domain clients have to be setup via Group Policy. For workgroup clients, you would have to make registry changes; see:
To manually search and download Windows updates, you can also use the Microsoft Windows Update Catalog via your browser. Unfortunately, it doesn't list available updates so you can't browse - all it's got is a search box where you can type the update that you're looking for.