if (document.images) {

img1on=new Image();                //Active images
img1on.src="images/ohome.jpg";
img2on=new Image();
img2on.src="images/oabout.jpg";
img3on=new Image();
img3on.src="images/oservice.jpg";
img4on=new Image();
img4on.src="images/olinks.jpg";
img5on=new Image();
img5on.src="images/ocontact.jpg";
img6on=new Image();
img6on.src="images/otest.jpg";

img1off=new Image();                //Inactive images
img1off.src="images/bhome.jpg";
img2off=new Image();
img2off.src="images/babout.jpg";
img3off=new Image();
img3off.src="images/bservice.jpg";
img4off=new Image();
img4off.src="images/blinks.jpg";
img5off=new Image();
img5off.src="images/bcontact.jpg";
img6off=new Image();
img6off.src="images/btest.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");
}
}