head1_off = new Image();
head1_off.src = "/images/header/button_blank.gif";
head1_on = new Image();
head1_on.src = "/images/header/button_hover.png";

function hovr(k) {
    if (document.images)
        eval('document.head' + k + '.src=head1_on.src');
}

function hout(k) {
    if (document.images)
        eval('document.head' + k + '.src=head1_off.src');
}