If you have two interfaces on win2K and you have DHCP enabled to give default gateways, you will get two default gateways. Do netstat -r and notice two entries for 0.0.0.0. Win2K machines, however, do not load balance and it will only use one of the two default gateways. The default gateway that you will be using is the lower IP address of the two. If you want to ensure that you are using your wired LAN interface, you can change the metric associated with the wireless LAN default gateway to something higher than 1. You can do this locally through network settings(define the same gateway with a high metric) or have your DHCP server hand out wireless default gateway info with metric higher than 1.
kevin chung