[Dimensio]

Where do atheists go after they die anyway? Do they just kindof disappear, like "poof!" and cease to exist?

Well, given that there's little (as in none) evidence for consciousness carrying on after the cessation of chemical reactions in the brain, it's pretty much something like that. The "light at the end of the tunnel" is kind of like that little white dot you see on older televisions before it all goes black.