I have a Dell Inspiron 1750, but when I launch my webcam it doesn't work and here's the message:
"Close the other application to start your video"
"Fermez l'autre application de diffusion vidéo pour demarer la video"
This means that you cannot use your webcam until you've closed all the applications that are using the webcam. Use Task Manager and close all the applications that you know are related to webcam's functionality then restart Dell Webcam Center and it should work. However, you cannot use 2 different streams of the same application in two different applications.