I have been using BSD variants as my primary OS for a long time now, and i have to agree about OpenBSD kicking ass. Although i like FreeBSD alot better, most BSD variants have specialtys, ie: OpenBSD = fucking uber security, FreeBSD = uber network capabilities, NetBSD = uber number of platforms supported. I would be willing to bet that OpenBSD is about as secure as an OS as your going to find on the x86 platform, and on most other platforms as well.
Heres an excerpt from
this page, this is to show the diffrence in encryption strength between FreeBSD MD5, OpenBSD blowfish, and Kerberos which a common encryption method on Windoze server OS's
"Benchmarking: FreeBSD MD5 [32/32]... DONE
Raw: 4373 c/s real, 4417 c/s virtual
Benchmarking: OpenBSD Blowfish (x32) [32/32]... DONE
Raw: 342 c/s real, 346 c/s virtual
Benchmarking: Kerberos AFS DES [48/64 4K MMX]... DONE
Short: 162764 c/s real, 164408 c/s virtual
Long: 436838 c/s real, 441250 c/s virtual"
c/s = "characters a second"
notice how much faster kerberos can be cracked, also notice just how few characters a sec can be cycled on OpenBSD encryption