Was always confused by this field in the Windows network configuration.. or rather never looked it up. Among other things, it seems it’s used to decide which connection is “preferred” when there are multiple available.
You can use “route PRINT -4” to display your routing table. If you have multiple connections, then there should be multiple entries for 0.0.0.0, and the one with the lower metric takes precedence. You can cross reference hte Gateway addresses with what you see from “ipconfig /all”
Relevant KB article: http://support.microsoft.com/kb/894564
Apparently the metric is really supposed to represent the “cost” of sending stuff over that network, so in situations of ambiguity, the lowest one wins.
Another useful command from that article “netsh interface ip show address”