I bought a Dell Inspiron that came with built in Verizon mobile broadband (wireless 5700).  I went to AT&T Cingular today to switch, installed the software, but when I inserted their wireless "card" in the same built-in slot, i got an error message that said it could not read the SIM card.  When I stuck the SIM card in a device that plugged into a USB port, it connected.

 

Do I need to uninstall the Dell mobile drivers that the laptop came with?  Or, does the "slot" only work with the 5700 device.  Thanks for any help.