Apple uses HTTP Live Streaming protocol. VLC should be able to play it just fine. You will probably need a custom URL to feed VLC though. I'll paste the URL here once it's available.
Last time VLC on WinXP would crash after a few seconds trying to play the official apple stream. Check reddit.com/r/apple and someone will post up a list of "pirate streams". One of them worked great for me in Firefox on XP last time.
EDIT: Quick bash script for extracting VLC-playable URLs (when they're available):
UPDATE: Here are the links:/snowLeopardurl/ = http://p.events-delivery.apple.com.edgesuite.net/1309ouhbqdv...
/non-snowLeopard url/ = http://p.events-delivery.apple.com.edgesuite.net/1309ouhbqdv...
/Windowsurl/ = http://p.events-delivery.apple.com.edgesuite.net/1309ouhbqdv...
/iphoneurl / = http://p.events-delivery.apple.com.edgesuite.net/1309ouhbqdv...
/ipadurl/ = http://p.events-delivery.apple.com.edgesuite.net/1309ouhbqdv...
/voip/ = http://p.events-delivery.apple.com.edgesuite.net/1309ouhbqdv...