Not sure if its the compatibility issue however  while checking  further i came across this two  threads,thought it might me helpful: answers.microsoft.com/.../a2f074cf-be62-435e-b951-42dfbb9351c2 answers.microsoft.com/.../e9d017f8-5a91-499c-a557-1a00e3948ad0 Note:This is not a Dell suggested solution,its a Third party link and you can try the suggested steps as per your discretion.
Hi:  Upgraded my D620 WLAN card from original 3965abg to 4965agn for wireless-n support.  The card is correctly installed (w/ 3 antennas) and the driver installed correctly but there seems to be a conflict with Dell Quickset utility which gives the error "WiFi Catcher band is not compatible".  Tried uninstalling the Dell Quickset, but not sure it completely removed everything.  Installed Intel PROset/Wireless but still unable to connect.  Could not find a Quickset version for Win7 - from what I have read, it seems the Vista version is noted that it does not support 4965agn.  Not sure what I should do next... appreciate any guidance...  thanks!    Windows7 32bit Intel PROset/Wireless ver:  14.03.1000 Dell Quickset version: 8.2.14   --Barochan
D620 upgrade WLAN card to 4965agn 