Any security software shipped by Dell would not be set to block a wireless connection. It would only do so if you told it to.
Since you have provided little infomation on what you have done to get this to connect, let's start from the beginning. Which wireless network adapter do you have on the 1150? Does your wireless network adapter show up in Device Manager if you expand the listing for Network Adapters? If you open Network Connections, does a wireless network connection show up there? If so, what happens when you right click the wireless connection and select "View Available Wireless Networks"? Does the Airport show up in the list of avaiable wireless networks? If so, what happens when you select it and click on the Connect button?
Steve