I found a similar situation on experts-exchange.com. If you are using Windows XP the solution was basically the following:
Start > Control Panel > Network Connections (or Start > Run > ncpa.cpl)
Select both Local Area Network Connections
Right click on the selected connections and choose Bridge Connections
Then just connect your wireless router into LAN port 2. You might need to tweak your router's settings, depending on the manufacturer.
By far my favorite quote on dual LAN ports:
"Experts have pondered the multi-NIC question, and one of their best answers is that: If you get a short enough network cable, dual NIC's can make a convenient carrying handle for your MB." -Madwand