Finding the Bottleneck in a Gigabit Ethernet LAN?

guroove asks: "I have a small gigabit ethernet network at home, and I spent a lot of money getting gigabit NICs for all my computers and even bought cat 6 cabling. I only have 3 computers on the gigabit network (a Mac, a Windoze machine, and a Linux box) so instead of getting a switch, I triple NIC'd the Linux box, which I use as a gateway and a file server. After the network was complete, I wasn't satisfied with transfer rates, so I started a transfer of a very large file and found that the transfer rate was topping off at just over 145 Mbps (which is a far cry from 1000 Mbps). I'm wondering now where my bottleneck is. Is it the NICs? Are all gigabit NICs really giving us 1000 megabits per second? Is it the driver? Is it Samba? Could it be that the hard drives aren't fast enough? Does anyone have experience with gigabit home networking enough to know where the bottlenecks are? Does the current PCI technology even allow for bandwidth that high"