Can't you use the PHP time() object for this? Pass this value:
time()."000" // note the trailing zeroes
Call that serverTime and pass it as a query string:
echo "myFlashFile.swf?serverTime=".time()."000";
Then in your Actionscript:
myDate = new Date();
myDate.setTime(serverTime);
Chat Clussman
2010-05-10 20:41:19