I'm hovering around 10 MB/sec to and from my computers Windows 7, to the NAS and all compuetrs/switch is 1GB LAN connection, but they don't have jumbo frames in the NIC properties so I found a computer that does and has a ASUS motherboard with jumobo frames in the NIC properties and from that computer I have done a transfer to the NAS of a 3.5GB ISO image and getting around 14MB/sec, OS is XP Professional, not sure if enabling jumbo frames made it 4 MB/sec faster or XP Pro did, but that's the difference with jumbo frames enabled.
My NAS is RAID-1 anyway.
Still getting around 35 - 45MB/sec from computer to computer.
Just my 2 cents worth