When you say that it works fine with 2003 server, is that during testing on your local machine or were you using a browser to test the page?
Is this used to play music and not video? So for example,
src="qt.jpg" brings up an image in the player
qtsrc="icy://188.8.131.52:8700" is suppose to bring in the music?
That's not what I see when I go to that address.
I'm not real familiar with Quicktime but the think the address may be wrong.