Any excellent technical article on EFS by Mark Russinovich is available at www.windowsitpro.com/Articles/Index.cfm?ArticleID=5592&Key=Internals
Encrypting File System in Windows XP and Windows Server 2003: www.microsoft.com/technet/prodtechnol/winxppro/deploy/cryptfs.mspx
Windows Data Protection: http://msdn.microsoft.com/library/en-us/dnsecure/html/windataprotection-dpapi
Certificate Auto-enrollment in Windows XP: www.microsoft.com/technet/prodtechnol/winxppro/maintain/certenrl.mspx
Key Archival and Management in Windows Server 2003: www.microsoft.com/technet/prodtechnol/windowsserver2003/technologies/security/kyacws03.mspx