To connect a PC which has two network interfaces (one Ethernet and another wireless) to a LAN, you will want to create a default route to the wireless interface, assuming you are using the wiressless network to get to the Internet (WAN). Here is a link on how to set up a default route on a Windows machine:
Here is the command to add a default route(assume 192.168.201.1 is your WAN gateway)
route add 0.0.0.0 mask 0.0.0.0 192.168.201.1
You will also need to add a static route so that all traffic going to LAN are directed to the LAN gateway, instead of to WAN. Here is how:
route add 10.100.0.0 mask 255.255.0.0 10.100.0.1
Useful links:
http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/route.mspx?mfr=true
