This topic is interesting. Looking back, when the Old Testament talked about hell, it was referring to sheol, which is not the place of eternal torment that Christians view hell as today. Sheol, a Jewish term, simply refered to the place of the dead in general, not particularly the place of punishment for the wicked. In fact, everyone who died went to sheol. Now, sheol was believed to be divided into two compartments, one for the righteous dead and one for the wicked dead, separated by a chasm. This is actually the setting for Jesus' controversial parable of the rich man and lazarus. People confuse this parable with the Christian vision of hell, but this parable is actually taking place in sheol.
Now, when Christ died, scholars believe this created a shift in the afterlife dwelling of our souls. Those on the "good" side of sheol were ministered to by Christ himself and ushered up to heaven. Those on the bad side stayed where they are. Now when people die as Christians, they no longer go to the good side of sheol but rather go to heaven, while those who are not in Christ still go to the bad side.
Of course, some people believe that we don't go anywhere, but upon death get ushered into the final judgment where Christ goes through the Book of Life and says who's in and who's out. That doesn't seem to jive with a lot of Scripture though, as there would be no people in sheol, heaven, or hell right now if that's the case.
This, at least, is the thought process I understood it as.