I use an AEBS as my router and WiFi access point. My MBP uses WiFi normally. I also have an old PC running Ubuntu Linux that I'm setting up as a DLNA server, which connects to the AEBS via Gigabit Ethernet (no WiFi on this machine). I also use the Linux box as a secondary backup for my MBP. When I need to do that I connect the MBP to the AEBS using the Ethernet port. First time I did this I left AirPort on and the transfer didn't seem particularly fast, so I stopped the copy, turned AirPort off on the MBP and restarted the copy. This time it seemed much faster. I know there are many things that affect throughput, but it made me wonder how OS X decides which connection to use when both wired and wireless are available. Both are on the same sub-net. Does it always use the fastest connection? Will it "flip-flop" between the two? Do I need to turn AirPort off to guarantee/force it to use Gigabit?