You need a legitimate CD key to play the game. A while back I would have gone to Interplay for assistance but given their current situation you may want to bring the game back to the store where you purchased it. Explain the situation, they probably even have a computer you can prove the problem with. You'll either get another copy or a refund. Hope it works out!
And before you do all that make sure that you didn't mistake the letter "O" with the number "0" and that the letters are in their proper case size.