Vista uses wi-fi rather than Ethernet for LAN traffic?

Hi all,

I have a Vista laptop that generally uses wi-fi to connect to the
local network via, but sometimes I plug in the Ethernet (when I need
to do big file transfers).

If I open Task Manager > Networking tab, I can see that Web browser
traffic spikes up within the "Local Area Connection" -- however, local
file sharing (ie, copying files between the laptop and other PCs on
the LAN) is over the wi-fi.

Any advice? Thanks! -Scott