Game runs on one screen, cursor wanders onto other screens?

The wording of the title was a little verbose.

Essentially, I'm creating a fullscreen single monitor game. Easy.

I'm on a triple monitor setup, and the game runs on the center monitor. Good.

The problem is however, that despite the game being fullscreen, the cursors can move freely in the game world as well as the other screens. Clicking on these other screens obviously minimizes the game window.

My question is as follows - How can I restrict the mouse cursor to the confines of the 'game screen area'?

I do require the cursor for the game mechanics, so removing the cursor entirely isn't an option.