if (document.images) {
    servicesbuttonup       = new Image();
    servicesbuttonup.src   = "images/menu/nl_services_down.png" ;
    servicesbuttondown     = new Image() ;
    servicesbuttondown.src = "images/menu/nl_services_up.png" ;

    customersbuttonup       = new Image();
    customersbuttonup.src   = "images/menu/nl_customers_down.png" ;
    customersbuttondown     = new Image() ;
    customersbuttondown.src = "images/menu/nl_customers_up.png" ;

    toolsbuttonup       = new Image();
    toolsbuttonup.src   = "images/menu/nl_tools_down.png" ;
    toolsbuttondown     = new Image() ;
    toolsbuttondown.src = "images/menu/nl_tools_up.png" ;

    companybuttonup       = new Image();
    companybuttonup.src   = "images/menu/nl_company_down.png" ;
    companybuttondown     = new Image() ;
    companybuttondown.src = "images/menu/nl_company_up.png" ;

    contactbuttonup       = new Image();
    contactbuttonup.src   = "images/menu/nl_contact_down.png" ;
    contactbuttondown     = new Image() ;
    contactbuttondown.src = "images/menu/nl_contact_up.png" ;
}
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" );
    }
}