function showTab(num)
{
    var tab1 = document.getElementById('features');
    var tab2 = document.getElementById('additional');
    var tab3 = document.getElementById('shipping');
    var tab_bkg = document.getElementById('tab_bkg');
    var tab_btm = document.getElementById('tab_btm');

    var tab_con_1 = document.getElementById('tab_con_1');
    var tab_con_2 = document.getElementById('tab_con_2');
    var tab_con_3 = document.getElementById('tab_con_3');

    if ('1' == num) {
        tab_con_2.style.display = 'none';
        tab_con_3.style.display = 'none';
        tab_con_1.style.display = 'inline';

        tab1.src    = '/images/tabs/tab1_1_on.gif';
        tab2.src    = '/images/tabs/tab1_2_off.gif';
        tab3.src    = '/images/tabs/tab1_3_off.gif';
        tab_bkg.style.background = 'url(/images/tabs/tab1_bkg.gif)';
        tab_btm.src = '/images/tabs/tab1_btm.gif';
    } else if ('2' == num) {
        tab_con_1.style.display = 'none';
        tab_con_3.style.display = 'none';
        tab_con_2.style.display = 'inline';

        tab1.src    = '/images/tabs/tab2_1_off.gif';
        tab2.src    = '/images/tabs/tab2_2_on.gif';
        tab3.src    = '/images/tabs/tab2_3_off.gif';
        tab_bkg.style.background = 'url(/images/tabs/tab2_bkg.gif)';
        tab_btm.src = '/images/tabs/tab2_btm.gif';
    } else {
        tab_con_1.style.display = 'none';
        tab_con_2.style.display = 'none';
        tab_con_3.style.display = 'inline';

        tab1.src    = '/images/tabs/tab3_1_off.gif';
        tab2.src    = '/images/tabs/tab3_2_off.gif';
        tab3.src    = '/images/tabs/tab3_3_on.gif';
        tab_bkg.style.background = 'url(/images/tabs/tab3_bkg.gif)';
        tab_btm.src = '/images/tabs/tab3_btm.gif';
    }
}