Windowed game to fullscreen

For the past 1 to 2 months i have been making a simple child’s games.
Unity 4.0 Free . Building for windows.

The game is “2D”/Camera is static orthographic . The entire time during development i was building the game for
Default screen width 1024 height 768 and i was testing on windowed.
Now the game has to be in default Full screen. However all the images that i used for background(I have a plane) are with that size and when i switch to full screen it gets blurred as if with low quality. How do i make it that the background(plane) stay in the middle of the screen and not reside.(also the other objects)

I really do hope you can help me ;d.

Create one script, apply it on main camera:

public float orthographicSize = 5;
public float aspect = 1.33333f;

void Start()
    Camera.main.projectionMatrix = Matrix4x4.Ortho(
            -orthographicSize * aspect, orthographicSize * aspect,
            -orthographicSize, orthographicSize,
            camera.nearClipPlane, camera.farClipPlane);

Maybe set up a 1024x768 rect for the camera to draw into?