You want to assign a string to a PHP var. So you are working in PHP. When you are working in PHP, you don't have to place <?php of <? in front of every var.. :/
So do somthing like this:
<?php
$redText = "<td align=\"center\" height=\"1\" bgcolor=\"" . $color . "\"><strong><font size=\"2\" face=\"Arial, Helvetica, sans-serif\" color=\"red\">";
Like leatherback said: To print quotes without parsing errors, place a \ in front of them..