The dice are rigged; AI only wins because it cheats. Otherwise, it's an awesome game.
Stupid AI aside, this game is brilliant. It follows the board game rules perfectly and in my book is a lot more fun than playing on a board because you don't have to worry about getting everything set up. Risk II does all the work for you--you just play the game.
You can use the free WarZone client (ewarzone.com) to play Risk II over the internet, which is probably one of the main reasons the game is still so popular.
In spite of my whining about the AI, it isn't really all that bad unless you're picky about cheating. I'm still able to beat the cheating AI, but it doesn't seem fair to have them rolling sixes most of the time while your dice are actually random.