var img = new Array();

img[901] = new Image();  img[901].src="images/font_big.gif";
img[902] = new Image();  img[902].src="images/font_big_.gif";
img[903] = new Image();  img[903].src="images/font_def.gif";
img[904] = new Image();  img[904].src="images/font_def_.gif";
img[905] = new Image();  img[905].src="images/font_mini.gif";
img[906] = new Image();  img[906].src="images/font_mini_.gif";
img[909] = new Image();  img[909].src="images/head_form.gif";
img[910] = new Image();  img[910].src="images/head_form_.gif";

img[703] = new Image();  img[703].src="images/topic_old.gif";
img[704] = new Image();  img[704].src="images/topic_old_.gif";

function change_image(nam,num) {
        if(navigator.appVersion.charAt(0)>= 3) {
                document.images[nam].src = img[num].src;
        }
}