function togglere() {
thevalue = document.healthform.formdif.selectedIndex;
if (thevalue=="personal") {document.getElementById('info').style.visibility == 'block';}
}



 <form action="submit.cfm" method="post" name="Healthform" id="Healthform" target="hiddenframe"  style="padding:10px;">


<select  name="formdif" id="formdif" onselect="togglere()">
            <option value="--" selected="selected">Select Insurance or Info Type</option>
            <option value="personal">Personal And Family</option>
            <option value="business">Group And Business</option>
            <option value="life">Life Insurance</option>
            <option value="medicare">Medicare Insurance</option>
            <option value="https://www.temporaryinsurance.com/stm/(i12blu452ymv5xmx5hnpeyio)/GetQuote/">Short Term Insurance</option>
            <option value="http://ssdirector.eassuranthealth.com/agentlink.aspx?linkid=7B242136E58AF807">Student Health Insurance</option>
            <option value="dental">Dental Insurance</option>
            <option value="retirement">Retirement and 401k</option>
            <option value="agent">Become An Agent</option>
          </select>

</form>

Works fine using this on one of the option values onclick="document.getElementById('info').style.visibility = this.checked ? 'visible' : 'hidden'"