Microsoft's Windows 10 will be available as a free upgrade to Windows 7 and 8.1 users in July 2015. Enterprise version will be out later this year.
Main Security features are Application-vetting and biometric authentication.
Security features which are available in the first release:
1. Device Guard: To manage zero-day attacks by vetting applications that try to access a Windows 10 machine and its network.
2. Windows Hello : It’s a password-killer feature that uses biometrics to invoke Windows 10 devices rather than usual password mechanism.
3. Passport: Prompt user to verify that you have possession of devices before it authenticates on user behalf.