On my previous notebook, the Dell/Broadcom wireless adapter had an option to automatically disable wireless when a wired network is connected, so I never dealt with multiple active interfaces. My current system has an Intel wireless adapter, and they apparently haven't figured out how to turn it off when there is a wired connection. Unless I explicitly remember to disable wireless when docked, the connection is active.

That shouldn't be a problem (in theory), since the route metric will cause traffic to go over the fastest network (as indicated by the lowest metric in the routing table).

Apparently not - I'm running a backup and seeing the throughput at 25Mbps or so (which is consistent with 802.11g) when a perfectly good Gigabit Ethernet interface is also connected.

IPv4 Route Table
===========================================================================
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0    192.168.1.254    192.168.1.104     10
          0.0.0.0          0.0.0.0    192.168.1.254    192.168.1.109     25
        127.0.0.0        255.0.0.0         On-link         127.0.0.1    306
        127.0.0.1  255.255.255.255         On-link         127.0.0.1    306
  127.255.255.255  255.255.255.255         On-link         127.0.0.1    306

Windows has correctly identified the Ethernet interface (.104) and assigned it the lower (preferred) metric. So the Ethernet interface should be used exclusively, right?

Why is the Ethernet connection not being used? What other factors are involved? (This is with Windows 7 if it makes a difference)