SO fiddle

Test Fiddle mainly for SO Questions

by Nick Craver

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.4/themes/overcast/jquery-ui.css">
<select id="ddl_tech" onchange="document.getElementById('chk_techreview').disabled = ( this.options[this.selectedIndex].text == 'UNASSIGNED');">
    <option> UNASSIGNED</option>
    <option selected="selected">Other</option>
</select>

<input id="chk_techreview" type="checkbox" />