Who will go to Heaven?

I know one of the big questions some Christians have is will those who were not told about Christ go to heaven. While I was growing up, this was sometimes a touchy subject. Many people don't want to believe in a God who would allow people to go to Hell without being "given a chance" to know Jesus.

I have always known people who believe that those who were not introduced to Jesus will go to Hell. I believe this believe is based on John 3:16 and John 14:6.

However, I recently read Romans Chapter 2 and Romans 2:13 - 15 says, "For it is not those who hear the law who are righteous in God's sight, but it is those who obey the law who will be declared righteous. (Indeed, when Gentiles, who do not have the law, do by nature things required by the law, they are a law for themselves, even though they do not have the law, since they show that the requirements of the law are written on their hearts, their consciences also bearing witness, and their thoughts now accusing, now even defending them.)" (NIV)

Does this mean that Jesus will judge those who have not heard the law (i.e. have not been told about Jesus) based on their conscience?

This seems to go against what I was taught when I was younger, but I certainly can't simply dismiss it.