I was digging into an issue and saw lots of search result hits around
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
and the BufferPolicyReads value in particular all referring back http://support.microsoft.com/kb/319440 and some of them mentioned making the change on Domain Controllers and some of them mentioned making the change on Vista and/or Windows 7.
I just peeked at the source code and I can’t find any references to that value in anything but Windows XP SP3 and Windows Server 2003 SP2 so I expect use of it on say Windows 7 would be pretty useless. I can’t say for sure as I haven’t gone through the replacement code for that functionality governed by that reg key but I do expect it is the case.
Also since the functionality was implemented in the GINA (replaced by the Credential Provider in Windows Vista / Windows Server 2008) the change performed on a Domain Controller wouldn’t have helped a client machine.
joe