var btn_welcomeUp;
var btn_welcomDown;
var btn_servicesUp;
var btn_servicesDown;
var btn_opensourceUp;
var btn_opensourceDown;
var btn_whyUp;
var btn_whyDown;
var btn_newsUp;
var btn_newsDown;
var btn_contactUp;
var btn_contactDown;

if (document.images) {
    //welcome
    btn_welcomeUp       = new Image();
    btn_welcomeUp.src   = "img/Buttons/btn_welcome.gif" ;
    btn_welcomeDown     = new Image() ;
    btn_welcomeDown.src = "img/Buttons/btn_welcome-over.gif" ;
    
    //services
    btn_servicesUp       = new Image();
    btn_servicesUp.src   = "img/Buttons/btn_services.gif" ;
    btn_servicesDown     = new Image() ;
    btn_servicesDown.src = "img/Buttons/btn_services-over.gif" ;
    
    //opensource
    btn_opensourceUp       = new Image();
    btn_opensourceUp.src   = "img/Buttons/btn_opensource.gif" ;
    btn_opensourceDown     = new Image() ;
    btn_opensourceDown.src = "img/Buttons/btn_opensource-over.gif" ;
    
    //why
    btn_whyUp       = new Image();
    btn_whyUp.src   = "img/Buttons/btn_why.gif" ;
    btn_whyDown     = new Image() ;
    btn_whyDown.src = "img/Buttons/btn_why-over.gif" ;
    
    //why
    btn_newsUp       = new Image();
    btn_newsUp.src   = "img/Buttons/btn_news.gif" ;
    btn_newsDown     = new Image() ;
    btn_newsDown.src = "img/Buttons/btn_news-over.gif" ;
    
    //why
    btn_contactUp       = new Image();
    btn_contactUp.src   = "img/Buttons/btn_contact.gif" ;
    btn_contactDown     = new Image() ;
    btn_contactDown.src = "img/Buttons/btn_contact-over.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" );
    }
}