function getAppVersion()
		{
		appname= navigator.appName;
		appversion = navigator.appVersion;
		majorver = appversion.substring(0, 1);
		if ( (appname == "Netscape") && ( majorver >= 3 ) ) return 1;
		if ( (appname == "Microsoft Internet Explorer") && (majorver >= 4) ) return 1;
        return 0;
		}

function swtch(num, imgname) {
  if (getAppVersion()) {
 document[imgname].src = img[num].src;
}
}
<!--start toolbar items-->
imgsrc = new Array(36);
imgsrc[0] = "http://www.xanthos.com.au/images/nav_catalogue.gif";
imgsrc[1] = "http://www.xanthos.com.au/images/nav_catalogue_x.gif";
imgsrc[2] = "http://www.xanthos.com.au/images/nav_order.gif";
imgsrc[3] = "http://www.xanthos.com.au/images/nav_order_x.gif";
imgsrc[4] = "http://www.xanthos.com.au/images/nav_guarantee.gif";
imgsrc[5] = "http://www.xanthos.com.au/images/nav_guarantee_x.gif";
imgsrc[6] = "http://www.xanthos.com.au/images/nav_about.gif";
imgsrc[7] = "http://www.xanthos.com.au/images/nav_about_x.gif";
imgsrc[8] = "http://www.xanthos.com.au/images/nav_references.gif";
imgsrc[9] = "http://www.xanthos.com.au/images/nav_references_x.gif";
imgsrc[10] = "http://www.xanthos.com.au/images/nav_links.gif";
imgsrc[11] = "http://www.xanthos.com.au/images/nav_links_x.gif";
imgsrc[12] = "http://www.xanthos.com.au/images/nav_register.gif";
imgsrc[13] = "http://www.xanthos.com.au/images/nav_register_x.gif";
imgsrc[14] = "http://www.xanthos.com.au/images/nav_search.gif";
imgsrc[15] = "http://www.xanthos.com.au/images/nav_search_x.gif";
<!--end toolbar items-->
<!--start nav bar items-->
imgsrc[16] = "http://www.xanthos.com.au/images/cat_classic.gif";
imgsrc[17] = "http://www.xanthos.com.au/images/cat_classic_x.gif";
imgsrc[18] = "http://www.xanthos.com.au/images/cat_egypt.gif";
imgsrc[19] = "http://www.xanthos.com.au/images/cat_egypt_x.gif";
imgsrc[20] = "http://www.xanthos.com.au/images/cat_mideast.gif";
imgsrc[21] = "http://www.xanthos.com.au/images/cat_mideast_x.gif";
imgsrc[22] = "http://www.xanthos.com.au/images/cat_chinese.gif";
imgsrc[23] = "http://www.xanthos.com.au/images/cat_chinese_x.gif";
imgsrc[24] = "http://www.xanthos.com.au/images/cat_precolumb.gif";
imgsrc[25] = "http://www.xanthos.com.au/images/cat_precolumb_x.gif";
imgsrc[26] = "http://www.xanthos.com.au/images/cat_stheastasia.gif";
imgsrc[27] = "http://www.xanthos.com.au/images/cat_stheastasia_x.gif";
imgsrc[30] = "http://www.xanthos.com.au/images/cat_auction.gif";
imgsrc[31] = "http://www.xanthos.com.au/images/cat_auction_x.gif";
imgsrc[32] = "http://www.xanthos.com.au/images/cat_new.gif";
imgsrc[33] = "http://www.xanthos.com.au/images/cat_new_x.gif";
imgsrc[34] = "http://www.xanthos.com.au/images/cat_archive.gif";
imgsrc[35] = "http://www.xanthos.com.au/images/cat_archive_x.gif";
<!--end cat bar items-->
<!--start special items-->
imgsrc[28] = "http://www.xanthos.com.au/images/btn_auction.gif";
imgsrc[29] = "http://www.xanthos.com.au/images/btn_auction_x.gif";
<!--end special items-->

if (getAppVersion()){
        img = new Array(36);
        for (i = 0; i < imgsrc.length; i++)
				{
                img[i] = new Image();
                img[i].src = imgsrc[i];
        }
}