With the move into V6.1, CTUpdate has been renamed WSUSOffline and has been retaken over by the original author. Basically WSUSOffline allows you to download OS / Offices updates from Microsoft (of different version whether you have them installed or not). There are options to burn to CD/DVD or keep in a portable HDD which you can carry around and patch other system. In short, download once, patch many systems. Not to mention its pretty effective if you go to low bandwidth areas.
Check it out at: