<iframe class="transparent" name="I2" scrolling="no" src="http://reek.ru" width="498" height="77" align="left" onmouseover="this.src = 'http://reek.ru'"></iframe>
Или:
<iframe class="transparent" name="I2" scrolling="no" src="http://reek.ru" width="498" height="77" align="left" onmouseover="this.contentWindow.location.reload(false)"></iframe>