In tip 2074, I introduced Windows File Protection. In tip 2075, I describe some registry entries for the System File Checker.

Here is a more comprehensive list, all located at HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon.

 Value Name   Type   Default   D e s c r i p t i o n 
 SFCDisable   REG_DWORD   0 - Professional
 4 - Servers
 
 0 = enabled
 1 = disabled, prompt at boot to re-enable
 2 = disabled at next boot only, no prompt to re-enable
 4 = enabled, with popups disabled
 NOTE: Options 1 and 2 require a kernel debugger to be hooked.
 
 SFCScan   REG_DWORD   0   0 = do not scan protected files at boot
 1 = scan protected files at every boot
 2 = scan protected files once
 
 SFCQuota   REG_DWORD   See tip 2075   See tip 2075 
 SFCDllCacheDir   REG_EXPAND_SZ   See tip 2075   See tip 2075 
 SFCShowProgress   REG_DWORD   0   0 = SFC progress meter is not displayed
 1 = SFC progress meter is displayed
 

NOTE: Take a look at HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Setup\SourcePath. If you copy the I386 folder from your CD-ROM and change the drive letter, WFP and SFC /SCANNOW won't prompt for the CD-ROM. You will have to restart for this setting to take effect.