The driver thing is "reaktek not on Windows". I don't know what the design decision to use reaktek instead of Intel was about on early Atom servers, but they all use Intel Ethernet now. I've put Intel PCIe cards in them when I don't want to bother with the realtek driver. A large MTU is only going to be beneficial within our network though since the internet at large is 1500. There's a program called tracepath which is like traceroute, but it will show you where MTUs change, although more providers are enabling jumbos over time. Sometimes old ways die hard though: we have a FastE through Verizon fiber and they insist on hard setting speed/duplex and 1500 MTU.
Even though individual servers have gigabit connections to our core switch they don't have dedicated gigabit to the internet unless it's billed as a committed rate service. There are places where multiple diverse GigE or 10Gig is cheap and easy to get, but unfortunately for us Nevada is not one, although I'm always trying to improve that. Some of our providers don't even offer Ethernet at all, like Sprint, and we can only order DSx or OCx circuits from them. You may want try a large DVD ISO with bittorrent (like one from a popular Linux distro). Because of the multiple-stream nature of torrents they will enter our network over multiple paths and aggregate higher speeds. I would even try setting the MTU back to 1500 in case the reaktek driver is confused and impacting performance.
Seth Mattinen, Roller Network LLC