Tim
You mentioned the Ultra4 has an Atom D410 CPU - single core 1.67Ghz.
You also mentioned the Pro4 has an Atom D510 CPU - dual core 1.67Ghz.
You did not mention the Ultra4Plus which has the same (more limited) feature set as the Ultra4 but has the dual core D510 like the Pro2.
The Pro series adds the following features (not available on Ultra):
Active Directory
SNMP
Secure RSYNC (Ultra has RSYNC but not over SSL)
Snapshot
VLAN
LAN teaming/failover
Additional 2 year warranty
Hope that helps to clarify things.
You mentioned the Ultra4 has an Atom D410 CPU - single core 1.67Ghz.
You also mentioned the Pro4 has an Atom D510 CPU - dual core 1.67Ghz.
You did not mention the Ultra4Plus which has the same (more limited) feature set as the Ultra4 but has the dual core D510 like the Pro2.
The Pro series adds the following features (not available on Ultra):
Active Directory
SNMP
Secure RSYNC (Ultra has RSYNC but not over SSL)
Snapshot
VLAN
LAN teaming/failover
Additional 2 year warranty
Hope that helps to clarify things.
