just to add my 2 cents (because they're useless in australia, and have been for well over a decade)...
I like Tool. I've only managed to hear Vicarious from their latest album, due to my inability to be a pirate at the moment. I wish their guitarist would learn a different riff. It seriously sounds like a blend of about 3 of their previous songs, and different lyrics. If their whole album sounds like that, i'd rather stick with lateralus.
I haven't heard of 2 of the 3 groups that were mentioned as the next step in fanboyism, but Dream Theater makes me wish I hadn't stopped taking drugs, because their stuff is too odd for me. Or maybe it's just the album "awake"s fault.
Overrated band --> Mars Volta. I'm sorry people, but to me, 15 minutes of dischordant needling does not a song make.