This was generally a common problem with early C5's but on most later C5's, the windows were adjusted to provide more pressure against the seals. The windows can be adjusted to 'fix' this. There is probably a thread here somewhere about how to adjust the windows to provide more pressure against the seals to keep them from popping out at speed. Since yours is a 2004, take it to the dealer and have them adjust it.
Another thing you can do to help is shut off the A/C when you want to go really fast. When the A/C is working, it allows outside air to flow into the car. At speed, this can increase the pressure inside the car and cause the windows to 'blow out' away from the seals. Another reason to have them adjusted to lean in a little more.
Our old '98 did that above 110 and it was real annoying at 165. Our 03 vert doesn't seem to have the problem - at least not up to 147 anyway.
