Wanderer, thanks for posting the question with good intentions. A lot of people who have issues with us don't even bother asking, or if they do, it's to vent their exasperation with what they think they know about us. After participating in the "Blasphemy Challenge" on YouTube, I can't help but be reminded of that fact. So I really appreciate you asking.
As to what it is, atheism is just the lack of belief in God. Note that atheism as a single word doesn't automatically imply one is non-religious, only non-god believing. Some religions are atheistic. Most, if not all of we atheists here, are agnostic atheists. http://atheism.about.com/ is a good place to learn more about atheism in detail.
If there was proof of God, I probably wouldn't have become an atheist. I'm not an atheist due to my WT experiences--or at least, not directly because of them. The evidence just seems to lean against the existence of God. I suspect that if I'm wrong and there is a god of any sort, it is a deistic one. I actually do doubt the existence of the Christian God, as mentioned in the Bible. I also agree with those who said he isn't presented as a very nice guy in the Bible (WT version or not). If that particular god does exist, I wouldn't worship Him because He deserves it. The best I could offer is deference out of fear to avoid getting zapped with leprosy or turned into a pillar of salt, or something. I doubt the existence of the supernatural as well. I don't see how life after death is possible, but just like everything else I say or think, I could always be wrong.
As far as meaning of life stuff goes, I don't know that the universe owes us a meaning to live. Why should we expect to be given one? We can't be lazy about this--we have to find our meaning ourselves. We were born to live and have to create our purpose. We have to use our time well instead of writing off this life in favor of some other. That's how I feel about it. Far as I'm concerned, when we look in the mirror, that's all that we are. Our minds, however, can do wonderful and even awe inspiring things. I see nothing depressing about that. It just seems like a bit of an ego trip to reject atheism on this basis to me. If it's just the way it is, and has always been, then no biggy. You know? Atheism, as mentioned by others, doesn't pretend to answer such questions. There is no philosophy, dogma, or worldview implied by atheism.
BTW, thanks for your open mindedness as well, Olvidado. :-)
IsaacJ