You have two choices, use either but *not* both together.
At design time, set .WindowState of the form to 2 (maximized)
OR at runtime, use

Screen.Width
Screen.Height
Screen.TwipsPerPixelX
Screen.TwipsPerPixelY

to calculate the size of the current screen and resize your window accordingly. you can always add up
more twips to cover more than the actual screen resolution with this code.

hope this helps!