The Windows 7 security story has three main chapters that have received a fair amount of attention: DirectAccess, BitLocker To Go, and AppLocker. With these, as well as features such as BranchCache and enhancements to UAC (user account control), officials at Microsoft have said they feel they are pushing out their most secure operating system yet.

http://www.eweek.com/c/a/Security/Windows-7-Security-Story-May-Appeal-to-Enterprises-549002/

-Urs