How to play Unreal Turnament 2004 online?

Hi, I am a UT fan. I want to play this game online. But it says "Game server denied, Invalid CD key". Got any idea that will work? Can I play it using GameSpy Arcade? Hey come on, I am waiting for your response!!!

The game is telling you the problem. You need a valid CD-Key to play online. Since the game is only about $10 now at every store, just buy it. As you know, it is worth the money.