I want to congradulate the Zentyal TEAM, for a LINUX based SBS is the best, especialy for me, comming from Microsoft based servers ( ISA and TMG )
If you could manage to have a Reverse Proxy module and DNS sync, it will decimate all
No problems upgrading from 3.0 ( x64 )
Zentyal is installed as a VM - works like a charm ( 2 cpu-s and 2 gb ram )