if (document.images) {
        homebuttonup       = new Image();
        homebuttonup.src   = "images/homedown.gif" ;
        homebuttondown     = new Image() ;
        homebuttondown.src = "images/homeup.gif" ;
    
        probuttonup       = new Image();
        probuttonup.src   = "images/productdown.gif" ;
        probuttondown     = new Image() ;
        probuttondown.src = "images/productup.gif" ;
        
        serbuttonup       = new Image();
        serbuttonup.src   = "images/servicedown.gif" ;
        serbuttondown     = new Image() ;
        serbuttondown.src = "images/serviceup.gif" ;
        
        aboutbuttonup       = new Image();
        aboutbuttonup.src   = "images/companydown.gif" ;
        aboutbuttondown     = new Image() ;
        aboutbuttondown.src = "images/companyup.gif" ;
        
        conbuttonup       = new Image();
        conbuttonup.src   = "images/contactdown.gif" ;
        conbuttondown     = new Image() ;
        conbuttondown.src = "images/contactup.gif" ;
    }
    function buttondown( buttonname )
    {
        if (document.images) {
          document[ buttonname ].src = eval( buttonname + "down.src" );
        }
    }
    function buttonup ( buttonname )
    {
        if (document.images) {
          document[ buttonname ].src = eval( buttonname + "up.src" );
        }
    }