Thanks for the suggestion.
I'm currently running x86_64 Solaris 10 and CentOS 3.8 (Final) in an lx branded zone. But Zimbra Collaboration Suite (ZCS) is not supported on this verions of CentOS.
My intention is somehow to get ZCS running in a virtual machine. VirtualBox did not work out, I could not get ZCS installed, the virtual machine would just crash, no error messages anywhere. Both 32 & 64 bit did the same.
I'm considering KVM, as my current server H/W does support virtualizion, but I'm loath to move away from x86 Solaris, I mean my uptime is over 3 months without a reboot
-- Solaris is just so rock solid.