OS Suggestion - Network Servers, Open Source

Hello,

I have a network with about four SuSE 10.0 boxes on it, used as servers, and another one used as a desktop.

I am looking to add a firewall/router/DHCP server/NAT box, a storage server, and a VPN server. I want machines that have stable, fault-tolerant (and crash tolerant) OS's. And a good, strong firewall.

My options are as follows:
Stick with SuSE 10.0
CentOS
Solaris 10
FreeBSD

Any suggestions? Not just personal opinions, but I'm interested in proven stability and reliability, and intrgration with existing Linux (SuSE) boxes.

Ubuntu 6.06 Linux:

http://www.ubuntu-linux.net