isIE = (navigator.appName == 'Microsoft Internet Explorer');
isV5 = (parseFloat(navigator.appVersion)>=5.0);

if (document.images) {
	rollOvers = 1;
} else {
	rollOvers = 0;
}

loaded = 0;

function loadImg() {
	if (rollOvers) {
		menu01On = new Image();
		menu01On.src = "image/bt_01_on.gif";
		menu02On = new Image();
		menu02On.src = "image/bt_02_on.gif";
		menu03On = new Image();
		menu03On.src = "image/bt_03_on.gif";
		menu04On = new Image();
		menu04On.src = "image/bt_04_on.gif";
		menu05On = new Image();
		menu05On.src = "image/bt_05_on.gif";
		menu06On = new Image();
		menu06On.src = "image/bt_06_on.gif";
		

		menu01Off = new Image();
		menu01Off.src = "image/bt_01_off.gif";
		menu02Off = new Image();
		menu02Off.src = "image/bt_02_off.gif";
		menu03Off = new Image();
		menu03Off.src = "image/bt_03_off.gif";
		menu04Off = new Image();
		menu04Off.src = "image/bt_04_off.gif";
		menu05Off = new Image();
		menu05Off.src = "image/bt_05_off.gif";
		menu06Off = new Image();
		menu06Off.src = "image/bt_06_off.gif";
				
		loaded = 1;
	}
}

function switchOn(imgName) {
	if (loaded == 1) {
		imgOn = eval(imgName+"On.src");
		document[imgName].src = imgOn;
	}
}

function switchOff(imgName) {
	if (loaded == 1) {
		imgOff = eval(imgName+"Off.src");
		document[imgName].src = imgOff;
	}
}

if (isIE || isV5) {
	loadImg();
}