You could try out GuildWars.
It's free to play once you've got it, and you can make it to max level (20) in four days or less if you go at it.
The storyline is mission based and is well suited to short bursts of play, and the PvP is very active, so it's easy to get into.
It's easy to learn and hard to master, but it's not a game for everybody.
But it's well suited for casual and hard-core gamers alike.
It's also the most balanced PvP heavy game there is.
It's free to play once you've got it, and you can make it to max level (20) in four days or less if you go at it.
The storyline is mission based and is well suited to short bursts of play, and the PvP is very active, so it's easy to get into.
It's easy to learn and hard to master, but it's not a game for everybody.
But it's well suited for casual and hard-core gamers alike.
It's also the most balanced PvP heavy game there is.