Personally I think they are certainly there, as how could it be just us? -.-
What do you mean? There is no proof that there is intelligent life besides us, there is no reason to assume that there is intelligent life out there. I suppose it's fair to say intelligent life might evolve or might've evolved sometime or somewhere. But we don't know how likely it is for intelligent life to develop.
Yeah they do exist, the government just kills/bribes anyone that can prove it.
Well, you'd have to be kind of dumb to say that there are no other intelligent life forms in our galaxy alone, muchwise the rest of the universe. Look at Drake's Equation; something definitely exists. As far as Roswell, I'm not too sure. If an extraterrestrial craft did crash, and a being was recovered, the government definitely wouldn't tell the populous. Shit would go down, and people would probably die over it. I would love to know if it was a creature, but I also respect that the government is a pretty intelligent group of people. I'm sure their cost-benefit analysis yielded that it would be best not to tell us if it did happen.
I personally believe that E.Ts do exist, and that they have definitely visited Earth. There's too much pointless attention that's been drawn to them. Ridiculously elaborate crop circles, and such. I think we'll find out eventually. And if the world does end in 2012, I hope it's by some sort of intelligent alien life. That would be a cool way to die.