if (document.images) {
    img1_open           = new Image();
    img1_closed         = new Image();
    img2_open           = new Image();
    img2_closed         = new Image();

    img3_open           = new Image();
    img3_closed         = new Image();

    img4_open           = new Image();
    img4_closed         = new Image();

    img5_open           = new Image();
    img5_closed         = new Image();


    img1_closed.src      = "img/o_firmie.jpg";
    img1_open.src    = "img/o_firmie_hover.jpg";
    
    img2_closed.src      = "img/oferta.jpg";
    img2_open.src    = "img/oferta_hover.jpg";

    img3_closed.src      = "img/formularz.jpg";
    img3_open.src    = "img/formularz_hover.jpg";
    
    img4_closed.src      = "img/kontakt.jpg";
    img4_open.src    = "img/kontakt_hover.jpg";

    img5_closed.src      = "img/ogloszenia.jpg";
    img5_open.src    = "img/ogloszenia_hover.jpg";
}


function over(i)
{
    if (document.images)
        eval('document.img'+i+'.src=img'+i+'_open.src');
}

function out(k)
{
    if (document.images)
        eval('document.img'+k+'.src=img'+k+'_closed.src');
}