Honestly I don't know, how could anyone? but I agree with someone who said earlier that they thought it would be like before you were born, just nothingness. You wouldn't remember, you wouldn't think, you wouldn't be.
And on a lighter note If there does turn out to be a heaven or what have you then I hope whichever god is really the one and only god is fair enough that even though I am an atheist, the fact that I never, murdered, raped or was prejudiced towards someone simply because they had a different sex, race or belief system to me is enough to qualify me as "a good egg" in gods eyes. And if not, then thats not the kind of god I want to beleive in anyway (so I guess I'd be sitting in hell with my fngers in my ears and my eyes closed going "nope, I don't beleive in it so it ain't happening to me")