preloaded = false;
function PreloadImages() {
	if(document.images) {
		img_button_1 = new Image(); img_button_1.src = 'images/button_1.gif'; 
		img_button_1_o = new Image(); img_button_1_o.src = 'images/button_1_o.gif';

		img_button_2 = new Image(); img_button_2.src = 'images/button_2.gif'; 
		img_button_2_o = new Image(); img_button_2_o.src = 'images/button_2_o.gif';

		img_button_3 = new Image(); img_button_3.src = 'images/button_3.gif'; 
		img_button_3_o = new Image(); img_button_3_o.src = 'images/button_3_o.gif';

		img_button_4 = new Image(); img_button_4.src = 'images/button_4.gif'; 
		img_button_4_o = new Image(); img_button_4_o.src = 'images/button_4_o.gif';

		img_button_5 = new Image(); img_button_5.src = 'images/button_5.gif'; 
		img_button_5_o = new Image(); img_button_5_o.src = 'images/button_5_o.gif';

		img_button_6 = new Image(); img_button_6.src = 'images/button_6.gif'; 
		img_button_6_o = new Image(); img_button_6_o.src = 'images/button_6_o.gif';

		img_button_7 = new Image(); img_button_7.src = 'images/button_7.gif'; 
		img_button_7_o = new Image(); img_button_7_o.src = 'images/button_7_o.gif';

		preloaded = true;
	}
}
function ImgOn(imgName){
	if(preloaded) document[imgName].src = eval('img_' + imgName + '_o.src');
}
function ImgOff(imgName){
	if(preloaded) document[imgName].src = eval('img_' + imgName + '.src');
}