Thanks. Yeah it will do, saves you having to fetch all the records and preg_match them.
When you have your results, if you want to highlight the criteria in the results you could do something like..
while ($row = @mysql_fetch_array($results, MYSQL_ASSOC))
{
$field = $row['field_name'];
$field = str_replace($_POST['search_criteria'], '<font color="#336699">'.$_POST['search_criteria'].'</font>', $field);
echo $field;
}