nombre = navigator.appName;
version = parseInt(navigator.appVersion);

if ((nombre == "Netscape" && version >= 3) || (nombre == "Microsoft Internet Explorer" && version > 3)) 
ver = "correcta";
        else ver = "incorrecta";

if (ver == "correcta") {

nosa = new Image();
nosa.src = "../images/bot01in.gif";
nosb = new Image();
nosb.src = "../images/bot01.gif";

sera = new Image();
sera.src = "../images/bot02in.gif";
serb = new Image();
serb.src = "../images/bot02.gif";

nota = new Image();
nota.src = "../images/bot03in.gif";
notb = new Image();
notb.src = "../images/bot03.gif";

cola = new Image();
cola.src = "../images/bot04in.gif";
colb = new Image();
colb.src = "../images/bot04.gif";

clia = new Image();
clia.src = "../images/bot05in.gif";
clib = new Image();
clib.src = "../images/bot05.gif";

prea = new Image();
prea.src = "../images/bot06in.gif";
preb = new Image();
preb.src = "../images/bot06.gif";

infa = new Image();
infa.src = "../images/bot07in.gif";
infb = new Image();
infb.src = "../images/bot07.gif";

inia = new Image();
inia.src = "../images/bot_ini_in.gif";
inib = new Image();
inib.src = "../images/bot_ini.gif";

mapa = new Image();
mapa.src = "../images/bot_map_in.gif";
mapb = new Image();
mapb.src = "../images/bot_map.gif";

id1a = new Image();
id1a.src = "../images/idi_ing_in.gif";
id1b = new Image();
id1b.src = "../images/idi_ing.gif";

id2a = new Image();
id2a.src = "../images/idi_deus_in.gif";
id2b = new Image();
id2b.src = "../images/idi_deus.gif";

id3a = new Image();
id3a.src = "../images/idi_fran_in.gif";
id3b = new Image();
id3b.src = "../images/idi_fran.gif";

}

function abajo(imgName) {
        if (ver == "correcta") {
        document[imgName].src = eval(imgName + "a.src");
}
}
function arriba(imgName) {
        if (ver == "correcta") {
        document[imgName].src = eval(imgName + "b.src");
}
}