Wireless card

I just received my Dell laptop with built in wireless but cannot connect with my Linksys router.  I have two desk tops connected on ethernet cables.  My daughter's desk top is wireless and connected.  I have been on with Dell tech help twice but they don't seem to know what they are doing.  They sound like they are going through an instruction book rather than knowledge through experience.  Can anyone out there walk me through this?

Background info:  My wireless connection icon on the lower task bar has a red X through it;   When I go to "View Wireless Connection" , there is nothing in the "available wireless networks" box; The radio is on, with 4 green bars (lower task bar);  I can access the internet when I connect with an ethernet cable; I have disabled any encrypting or security devices.  Any help is appreciated.  Thanks.