How can I make my external monitor primary?

Hi,

I'm trying to figure out how to make my external monitor primary in Boot Camp for my Windows XP SP 3 partition. The "Use this device as the primary monitor." button is blanked out, meaning I'm unable to click it. This was the same with my last laptop (Dell Inspiron 6400) but I solved that problem by closing the lid. With my MacBook, when I close the lid the screen does not transfer everything to the larger monitor but simply leaves the screen on.

Any tips are appreciated.

I managed to solve the problem by going into the NVIDIA Control Panel.

Display > Set up multiple displays > Only use one display (Single)

It was initially on Dualview but I was not able to make my external monitor primary with this.

Thanks for reading anyhow.