A bit of a hack, but it seems that if you change an unneeded css property of the select, it will force an update.
$('#mySelect').css({margin: '0'}).append('<option value="0">(none available)</option>');
(Truncated example from yours, but principle should be the same.)
I tested this with ie7 on XP only.
patrick dw
2009-06-04 16:48:17