I would use standard Ethernet patch cables and connect both your PC and Netduino to the switch/router. The default gateway on your Netduino needs to be set to the IP address of your router (this should be also set on your PC). I would check your PC IP settings (IPCONFIG /all in a DOS box on the PC) and I assume net mask is correct 255.255.255.0, which will be the same for all devices on your network).
Once you have the right IP, mask and gateway set in the Netduino and powered up and connected to the router, you can ping it from your PC to see if it is seen (DOS box, PING 192.168.0.100). Does it reply to pings?