Doomtrooper, what most casual gamers don't see is that Quake3 is a sport, not a game. It is all about skill and skill development, and the fun a player gets from it (or not) is the same kind of fun you get from doing any other kind of sport. Which isn't quite what most other games aim for. DOOM3 will, in its first incarnation at least, have a completely different focus, and will probably appeal more to someone looking for a nice game type experience. It may not ever have the same foothold among the online gamers, because due to the way it was initially said to be programmed, it would be more open to cheating.
Then again, that never stopped CounterStrike from being popular.
Entropy