This will get 64-bit leap out of the way, and it shouldn't be a big deal if they decide to port to the Merced at a later date. Not having to concern itself with portability, the FreeBSD project has been more innovative and has tweaked the OS to the hilt for x86 performance. This optimization, combined with its stability, has given FreeBSD a reputation for holding up very well under heavy loads. If your task is to build a server that's going to take a lot of abuse, FreeBSD is a excellent choice. The emphasis of the OpenBSD project has been on stability and security.
Portability is high on the list as well.
As a close relative of NetBSD, version 2.3 of OpenBSD supports nearly all the same platforms. In the absence of these laws, OpenBSD can include strong encryption software without the legal hassles. Additionally, because of its security features, OpenBSD would be a good choice for a firewall or a secure server. FreeBSD 2.2.6, and OpenBSD 2.3.