WinRE (Windows Recovery Enviroment) is included by default in Windows 7, and this allows you to boot to WinRE to access recovery tools such as Complete PC image restore, system restore or to access a command prompt to run other useful command. You can access WinRE by booting a Windows 7 machine and press F8 and choose “Repair your computer”.
WinRE being included in Windows 7 is great but what is even greater is if you replace WinRE with DaRT (Diagnostics and Recovery Tools) included in Microsoft Desktop Optimization Pack (MDOP) which is available to Software Assurance customers. By doing this you get additional types of useful tools such as the ability to reset the passwords of local account, hotfix uninstall, crash analysis, reach computer management or use Windows Explorer. Now this is great! :)
The guide on how to replace WinRE with DaRT can be found at bink.nu.