Do external web cams work with MacBook Pro? I don't like using the built-in iSight camera as I want to adjust the angle etc.  Do external web cams still work with MacBooks with built-in camers?

I have a MacBook Pro 13" with Snow Leopard
Yes, most external webcams will work fine with a MacBook Pro with a built-in camera.  Just check the box for the camera before you purchase to ensure it's compatible.  Some webcams may come with bundled software which only works on Windows which is why you should check before you buy in case the software features are important to you.