function mouseover(name) {
    if (checkHover()) {
	document[name].src=MSFPpreload(hoverimage(name)).src;
    }
}

function mouseout(name) {
    if (checkHover()) {
	document[name].src=MSFPpreload(linkimage(name)).src;
    }
}

function checkHover() {
    return (((navigator.appName == "Netscape") && 
	     (parseInt(navigator.appVersion) >= 3 )) || 
	    ((navigator.appName == "Microsoft Internet Explorer") && 
	     (parseInt(navigator.appVersion) >= 4 ))); 
}

function MSFPpreload(img) {
    var a = new Image();
    a.src = img;
    return a; 
}

function linkbase(name)   {
    var endindex = 0;
    var bases = ['_a.gif','_p.gif','.gif'];
    for (var ii = 0; ii < bases.length; ii++) {
	endindex = document[name].src.lastIndexOf(bases[ii]); 
	if (endindex >= 0) {
	    break;
	}
    }
    return document[name].src.substring(0,endindex);
}
function linkimage(name)  { return linkbase(name)+".gif"; }
function hoverimage(name) { return linkbase(name)+"_a.gif"; }
function pageimage(name)  { return linkbase(name)+"_p.gif"; }