Most secure Operating-System?

[Alec Taylor]

Good evening,

What's the most secure operating system?

/me is thinking OpenBSD

Features required:
• TCP/IP Suite with IPv4 and IPv6 (yeah, I know, big security loss by
incorporating Internet access!)
• GUI
• Web-server (with HTTPS capabilities)
• LDAP+-Kerberos server for User auth
• CAS or similar for SSO
• Radius or (preferably) Diameter support
• Java support
• WINE compatible
• Multithreaded
• Multi-processor capable
• Wide architecture support (x86, x64, mainframes)

If my project proposal is successful, I will be implementing this
system to replace a  windows environment at one of the largest banks
in the country.

Thanks for all suggestions+advice,

Alec Taylor