function launchWindow(url,name) {
	win=window.open(url,name)
}
	
function rollover(theimage) {
	document[theimage].src = eval(theimage + '_on.src')
}

function rollout(theimage) {
	document[theimage].src = eval(theimage + '_off.src');
}
	
function popupCentre(url,name,width,height) {
	var titleBarHeight, windowBorderWidth
	titleBarHeight = 24
	windowBorderWidth = 4

	var screenWidth, screenHeight
	screenWidth = 800
	screenHeight = 600

	if (window.screen) {
		if (window.screen.availWidth) {
			// ok browser has the appropriate properties we need to centre it
			screenWidth = window.screen.availWidth
			screenHeight = window.screen.availHeight
		}
	}

	var windowWidth = windowBorderWidth + width + windowBorderWidth
	var windowHeight = titleBarHeight + height + windowBorderWidth

	var left = (screenWidth - windowWidth) / 2
	var top = (screenHeight - windowHeight) / 2

	win=window.open(url,name,'left='+left+',top='+top+',screenX='+left+',screenY='+top+',width='+width+',height='+height+',scrollbars=0,resizable=0,toolbar=0,location=0,directories=0,status=0,menubar=0,copyhistory=0')
	if (parseInt(navigator.appVersion) >= 4) { win.window.focus(); }
}