connecting to D-Link router

I am trying to secure my wireless connection on my Inspiron 1200 using a Dell wireless WLAN 1350 to my D-Link DI 524 router. My desktop system is set up for WEP 64Bit as is my Dell laptop. Without WEP I can connect without any problem with it enabled I can't connect to my desktop system. Does anyone have any ideas of what I have configure incorrectly?