When my laptop connects to the router, the desktop computer loses connection.

I would first upgrade the firmware MAKE SURE YOU SELECT THE RIGHT REVISION:

http://www.linksys.com/servlet/Satellite...e=download

Guide here: http://www.wrtrouters.com/guides/upgradefirmware/

MAKE SURE YOU DO THIS WIRE CONNECTED TO THE ROUTER THOUGH ETHERNET

Then reset the router to factory defaults: Guide : http://technicallyeasy.net/2008/01/how-t...-wireless/

Then, set up the wireless again: http://technicallyeasy.net/2007/09/secur...ss-router/