[keithwalton]

GBit was never intendid for raw point to point speed, but more being able to handle multiple simultaneous connections over the same lines. That and from programs running in memory linked to the memory on other machines.

There are multiple bottlenecks in your config,

hard drives will be the main one, in single drive mode peak brand new hughe ide / sata ones do 70mb/sec, raid 0 them and that figure nearly doubles.
15k rpm scsi drives do around 100mb/sec.

The way your gbit controller is connected is also usually a bottleneck.
If your using a pci card that has a max b/w of 133mb/sec (just over 1GBit) and this is shared with all other devices connected to the pci bus (usually hard drive controllers in older machines are as well)

Some motherboards connect GBe via the pci or pci-e bus to the southbridge (then north -> south bridge links can be a bottleneck).

The best implementation so far is in intel server (and some desktop boards) called csa, which connects the GBe to the northbridge