WinRE (Windows Recovery Environment) can be used to repair an installation of Vista when something goes wrong. You can launch WinRE by booting your Vista system from your Vista DVD—if you can find it when you need it. Alternatively, you can create a second partition of 1GB size on your computer and install Vista on the main partition and WinRE on the small partition. That way you always have WinRE handy whenever you may need it.
So if you've deployed Vista RTM computers with a WinRE RTM partition, do you have to update the WinRE partition to SP1 when you update your operating system to SP1? The answer is, No, you don't—WinRE RTM is completely compatible with the Vista SP1 operating system. However, you may want to update your WinRE RTM partition to WinRE SP1 anyways because of bug fixes in WinRE made in this service pack.