Just transferred a blu-ray from my main PC to my server. From here to there it traverses three switches, all three of which are gigabit speed. Getting some good speeds:
Theoretical limit should be 125MByte/sec. I suspect I don't reach that speed due not only to overhead from both layer 2 and 3, but also SMB (aka windows file sharing) has a bit of overhead on its own.
I've enabled jumbo frames, as all devices on my network support it, but I doubt SMB will transmit packets with an MTU that size. If it did, I'd probably see another 10MByte increase.
At the center of my network is one of these:
Very cheap but VERY good; not only does jumbo frames but has a 16 gig backplane. This thing outperforms the name brand switches that cost easily twice as much. As an added bonus, it uses such little power that it runs cool to the touch even during peak usage.
At each end of the network is an Asus RT-N16, serving as the main router, switch, and access point, and Netgear WNR3500L serving as a secondary access point and switch. Both run tomato firmware and support jumbo frames, 802.11n 300Mbit 40Mhz. I do this because wifi doesn't quite work across the entire house with just one access point.
I trudged through the attic and ran Cat5e and RG6 wire to every room in the house, cleanly installing it as an ethernet/coax jack on the walls:
EDIT: Internet pipe: