if (document.images) {
img1on = new Image();           
img1on.src = "media/index/profile_on.jpg";  
img2on = new Image(); 
img2on.src = "media/index/collaboration_on.jpg";  
img3on = new Image(); 
img3on.src = "media/index/products_on.jpg";  
img4on = new Image();           
img4on.src = "media/index/quality_on.jpg";  
img5on = new Image();           
img5on.src = "media/index/iform_on.jpg";  

img1off = new Image();          
img1off.src = "media/index/profile.jpg";  
img2off = new Image();
img2off.src = "media/index/collaboration.jpg";  
img3off = new Image();
img3off.src = "media/index/products.jpg";  
img4off = new Image();          
img4off.src = "media/index/quality.jpg";  
img5off = new Image();          
img5off.src = "media/index/iform.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");
        }
}