Buon giorno, stò utilizzando uno script che mi permette, con l'onmouseover su un link, di poter vedere in anteprima, in un piccolo riquadro, l'immagine del relativo sito.

Ora, questo script funziona con tutti i browser tranne I.E. 6 e 7.
Vi posto il codice, sperando vi sia utile per capire dov'è l'errore.
Nel arc90_linkthumb.js
codice:
var arc90_navigator = navigator.userAgent.toLowerCase();
var arc90_isOpera = arc90_navigator.indexOf('opera') >= 0? true: false;
var arc90_isIE = arc90_navigator.indexOf('msie') >= 0 && !arc90_isOpera? true: false;
var arc90_isSafari = arc90_navigator.indexOf('safari') >= 0 || arc90_navigator.indexOf('khtml') >= 0? true: false;
var arc90_linkThumbUseClassName = true;

var arc90_linksources = [['http://images.websnapr.com/?size=s&url=', 202, 152],
						  ['http://thumbnails.alexa.com/image_server.cgi?size=small&url=', 160, 120],
						  ['http://msnsearch.srv.girafa.com/srv/i?s=MSNSEARCH&r=', 160, 120]];
var arc90_linksource = 0;

function arc90_linkpic() {
	var b = document.domain;
	var A = document.getElementsByTagName('A');

	for (var i = 0, l = A.length, c = 0; i < l; i++) {
		var a = A[i];
		var h = a.href;
		if ((b == '' || h.indexOf(b) < 0) && h.indexOf('://') > 0 && ((arc90_linkThumbUseClassName && a.className.indexOf('linkthumb') >= 0) || !arc90_linkThumbUseClassName)) {
			try {
				a.className += ' arc90_linkpicLNK';
				if (a.id == '')
					a.id = 'arc90_link'+ i;
				var d = arc90_newNode('div', 'arc90_linkpic'+ i, 'arc90_linkpic');
				var m = arc90_newNode('img', '', 'arc90_linkpicIMG');
				// var n = h.replace(/[^:]*:\/\/([^:\/]*)(:{0,1}\/{1}.*)/, '$1');
				var n = escape(h);
				m.src = arc90_linksources[arc90_linksource][0] + n;
				m.width = arc90_linksources[arc90_linksource][1];
				m.height = arc90_linksources[arc90_linksource][2];
				m.style.width = arc90_linksources[arc90_linksource][1] +'px';
				m.style.height = arc90_linksources[arc90_linksource][2] +'px';
				m.border = 0;
				m.alt = '[Picture of '+ n +']';
				m.title = a.title;
				d.style.zIndex = '9999';
				d.style.position = 'absolute';

				d.appendChild(m);
				document.body.appendChild(d);

				arc90_addEvent(a, 'mouseover', function () { arc90_showThumb(arc90_isIE? event.srcElement.id: this.id); } );
				arc90_addEvent(a, 'mouseout',	function () { arc90_hideThumb(arc90_isIE? event.srcElement.id: this.id); } );
			} catch(err) {
				a = null;
			}
		}
	}
}

function arc90_showThumb(id) {
	try {
		var k = document.getElementById(id);
		var top = arc90_findDimension(k, 'Top');
		var lnh = arc90_getStyle(k, 'lineHeight', 'font-size');
		var default_height = 20;

		if (!lnh)
			lnh = default_height;
		else if (lnh.indexOf('pt') > 0)
			lnh = parseInt(lnh) * 1.3;
		else if (lnh.indexOf('em') > 0)
			lnh = parseInt(lnh) * 10;
		else if (lnh.indexOf('px') > 0)
			lnh = parseInt(lnh);
		else if (arc90_isNumeric(lnh))
			lnh = parseInt(arc90_isIE? lnh * 10: arc90_isOpera? lnh/100: lnh); // IE brings back em units
		else
			lnh = default_height;
		var lft = arc90_findDimension(k, 'Left');
		var nlf = arc90_findMatchingDimensionViaNodes(k, 'Left', lft, 0);
		var pid = id.replace(/arc90_link/, 'arc90_linkpic');
		var p = document.getElementById(pid);
		p.style.display = 'block';
		p.style.top = (top + (arc90_isIE && nlf? lnh + 8: 4) + lnh) + 'px';
		p.style.left = lft + 'px';
	} catch(err) { return; }
}

function arc90_hideThumb(id) {
	try {
		var k = document.getElementById(id);
		var pid = id.replace(/arc90_link/, 'arc90_linkpic');
		var p = document.getElementById(pid);
		p.style.display = 'none';
	} catch(err) { return; }
}

function arc90_getStyle(obj, styleIE, styleMoz) {
	if (arc90_isString(obj)) obj = document.getElementById(obj);
	if (obj.currentStyle)
		return obj.currentStyle[styleIE];
	else if (window.getComputedStyle)
		return document.defaultView.getComputedStyle(obj, null).getPropertyValue(styleMoz);
}

function arc90_findDimension(obj, pType) {
	if (arc90_isString(obj)) obj = document.getElementById(obj);
	var cur = 0;
	if(obj.offsetParent)
		while(obj.offsetParent) {
			switch(pType.toLowerCase()) {
			case "width":
				cur += obj.offsetWidth; break;
			case "height":
				cur += obj.offsetHeight; break;
			case "top":
				cur += obj.offsetTop; break;
			case "left":
				cur += obj.offsetLeft; break;
			}
			obj = obj.offsetParent;
		}
	return cur;
}

function arc90_findMatchingDimensionViaNodes(obj, pType, matching, notMatching) {
	var cur = 0, counter = 0;
	notMatching = notMatching == null? -1: notMatching;
	if(obj.parentNode)
		while(obj.parentNode) {
			cur = arc90_findDimension(obj, pType);
			if (cur == matching && cur != notMatching)
				counter++;
			if (counter >= 2) return true;
			obj = obj.parentNode;
		}
	return false;
}

/* Events */
function arc90_isString(o) { return (typeof(o) == "string"); }

function arc90_isNumeric(o) { return (typeof(parseFloat(o).toString() == 'NaN'? 'xxx': parseFloat(o)) == "number" && parseFloat(o) != ''); }

function arc90_addEvent(e, meth, func, cap) {
	if (arc90_isString(e))	e = document.getElementById(e);

	if (e.addEventListener){
		e.addEventListener(meth, func, cap);
    	return true;
	}	else if (e.attachEvent)
		return e.attachEvent("on"+ meth, func);
	return false;
}

/* Nodes */
function arc90_newNode(t, i, s, x, c) {
	var node = document.createElement(t);
	if (x != null && x != '') {
		var n = document.createTextNode(x);
		node.appendChild(n);
	}
	if (i != null && i != '')
		node.id = i;
	if (s != null && s != '')
		node.className = s;
	if (c != null && c != '')
		node.appendChild(c);
	return node;
}

/* Onload */
arc90_addEvent(window, 'load', arc90_linkpic);
Nel Link.php dove ci sono i link ed il relativo .js
codice:
<link rel="stylesheet" rev="stylesheet" href="Link/tool_global.css" type="text/css" />

<script language="JavaScript" type="Text/JavaScript" src="Link/arc90_linkthumb.js"></script>
		<!--script language="javascript" type="text/javascript">
			// uncomment the following line to give thumbnails to all links
			arc90_linkThumbUseClassName = false;
		</script-->
		
<div id="container">



<u>Google</u>
</p>
</div>
Il Css tool_global.css, non lo inserisco, perchè ininfluente..

Grazie mille a tutti, come sempre.