There's a difference between arguing, debating, and sharing knowledge and opinions.
Arguing is all about the ego. Whoever shouts the loudest, types the fastest, garners the most supporters, or throws down the best insults wins. Except no one wins in an argument. Don't get involved with them, except maybe to pop off a shot to make your voice heard (For the sake of third parties) and then ignore the other person. If it goes beyond that, you'll gain nothing and lose time and energy.
Debates are supposed to be all about logic and stuff. Really, they're nothing but a formalized way of arguing, except the involved parties are expected to have a higher standard of fact checking, presentation, and conduct. Beyond that, though, you'll see a lot of the same spirit that creates an argument: Dominance is key. One person may win a debate, but neither will come out the better for it.
The sharing of knowledge and opinions is what you want. If two people can get together, go a step beyond "agree to disagree" and actually try to understand where the other is coming from, why they think that way, and compare those thoughts to their own thoughts and feelings, then you have something beautiful. It doesn't even have to end with the two people coming out with the same opinion in the end - As long as both understand the other, accept that their view does have some solid logical/emotional/spiritual ground to stand on, then they have both won. There are no losers, because everyone either admits that they were wrong at some point or comes to more fully understand the people that share opposing views without any feelings being hurt. It's hard to get a sincere experience going, and it's tenuous when it does, but it's worth the effort to keep it from becoming a debate.
I've actually been partially convinced to rescind some of my own opinions on these forums, and come to understand and appreciate other perspectives. Do I agree with all of them? Of course not, that's not the purpose of sharing thoughts and opinions. The purpose is understanding.
That's what you want to achieve. Avoid everything else, I say.
Also, that logical fallacies site looks like good reading.