Set a PictureBox Size

Hi all

I have a PictureBox on my form in Visual Basic 2010. On a 21" screen the PictureBox is too small and then there is a blank space. On a 14" screen, the PictureBox is just right. The form window is set to Maximized. 

I would like to know, how can I code the PictureBox to get the same size as the windows' size? I want the PictureBox to fit into the window on all Screen sizes. 

Thanks