Just received my U2412M and while I was setting it up the instructions said to connect it to my Mac via USB in step 5. On my Dell 2209WA I didn't have to connect the screen to my Mac via USB, it's currently connected to my Mac mini using the supplied Apple adapter. With the 24 inch Dell I am connecting it using a minidisplay port adapter. Do I really need to connect the U2412M via USB for it to work with my Mac? Thanks.