right well you people dont know what you're talking about you have to recreate the structure in memory and read it from memory, here you dont need to create the structure since it will be passed into point for you by GetCursorPos
code:
var point = Interop.Allocate(8);
Interop.Call("user32.dll", "GetCursorPos", point);
Debug.Trace("x: " + point.ReadDWORD(0));
Debug.Trace("y: " + point.ReadDWORD(4));