I can't speak much for how EQ2 is set up, although I agree with what has been said about WoW being very playable by the casual gamer. I've participated in both of the stress tests and heading into open beta i've learned quite a bit about why it's far superior to anything I ever got out of any other MMO.
While there are a smaller number of races and classes available in WoW they're all very very distinct, with races having a handful of special abilities/bonuses apart from your basic everyday attributes. Classes are pretty much in the same camp as that, generally getting 2-4 new skills two levels or so.
But enough about that -- the PvP system is quite interesting in that even on a PvP server, you're not always flagged for it. A number of things can turn on said flag, one of them being entering a 'contested territory'. I thought this was a great idea as it makes the that place actually, well,
contestable. While I haven't actually found one yet, there are going to be special areas called 'battlegrounds' that are essential large areas populated by players of both the horde and the alliance -- all with the goal of killing the others. You can also go on raids, although I haven't quite figured out how raiding parties work yet (think party of parties).
As for the PvE instance dungeons, essentially what happens is you get together a group (6 person max i believe) and head out to a dungeon. After you head down a ways you'll hit a swirling portal -- step through and your group is teleported into their very own version. That way you don't have to worry about 2 dozen guys camping the dragon.
Anyway, hope this answered some stuff for some people and wasn't just me babbling. Make sure to ask if you've got more specific wow questions
