According to the manual, if the monitor was bought from Dell we would have included the "Dell SP2009W Webcam Resource CD"?You do not need driver in Windows 7, only the Dell Webcam Central software.
(Liaison for Desktops, Alienware, Monitors)Quick link for Manuals and Drivers
You must connect the monitor USB cable from the monitor and plug it into a USB port on the rear of the computer. Also, if your running in a dual monitor setup, that might be confusing the issue. Setup the SP2009W as a single primary monitor and then test the Webcam.
Need a web cam driver to SP2208WFPt, because it'snot working for me, thanks in advance