if (document.images) {
teston = new Image();		// Active images
teston.src = "images/searchbutt-down.jpg"; 

testoff = new Image();		// Inactive images
testoff.src = "images/searchbutt-up.jpg";  
}

function imgOn(imgName) {

if (document.images) {
document[imgName].src = eval(imgName + "on.src");
}
}

function imgOff(imgName) {
if (document.images) {
document[imgName].src = eval(imgName + "off.src");
}
}