How to use my plug in cam on msn instead of my built in 1 x?

i have a laptop with a built in cam (advent) and i have a normal webcam wich i plug into my laptop and i can choose wich on to use but when i go on msn it uses my built in 1 and i dont like that one because the quility isnt as good does any1 no what and how to get my plug in Web cam to use on msn thanks x