Ammo GUI Display Bottom Right of Screen?

var bulletHudTexture : Texture;
var ammoCountRect : Rect = Rect(25,25,50,25);
var ammoStartX : int = 100;
var ammoY : int = 25;
var ammoSize : Vector2 = Vector2(2.316,15);
var ammoSpacing : float = 3;
var ammoDecorationHudRect : Rect = Rect(25,50,50,25);
var ammoDecorationTexture : Texture;

function OnGUI ()

{

    if (beingHeld)

    {        
        if (ammoDecorationTexture)

            GUI.DrawTexture( ammoDecorationHudRect, ammoDecorationTexture);
            
	for (var i : int = 1; i <= currentClip; i++)
	{
		GUI.DrawTexture(Rect(ammoStartX + ((i - 1) * (ammoSize.x + ammoSpacing)), ammoY, ammoSize.x, ammoSize.y), bulletHudTexture);
	}
	GUI.Label(ammoCountRect, currentClip.ToString() + "/" + currentExtraAmmo.ToString());
    }
}

How do I use Screen.height and Screen.width to make the GUI in the bottom right corner instead of the top left corner.

new Rect (Screen.width - 200, Screen.height - 40, 200, 40)