Heroism in the 21st Century

Image via WikipediaThe third season of the science fiction television show "Heroes" began and as usual caused me to ponder the idea of heroism. I did some research into the meaning of hero/heroine and found that it is a man or woman admired for his/her achievements and noble qualities.
Beginning with Greek mythology and throughout history, there have been military, scientific, political, religious, activist, and athletic heroes. A hero can be accepted worldwide such as Albert Einstein and Mahatma Gandhi, for example, and a hero can be very personal such as a sports hero, actor or activist.
Science Fiction and Fantasy, of course, has taken the idea of the hero and created some of the most interesting and inspiring stories. The characters can be related to such as Spider-Man who was an average person suddenly endowed with unusual powers that he uses for good, or a non-human, such as Superman who can perform unearthly acts such as fly. In the 3rd season of Heroes we have an element that is less than savory and use their powers for less than good. We see this same battle of good vs. evil in the X-Men series of movies where some use their powers for good and others for bad.
So I ponder the question brought to me through the medium of science fiction and fantasy that if we humans were able to utilize super powers would we be inclined to use these powers for selfless or selfish purposes? Real life heroes have worked for the betterment of humanity, in my opinion, so I wonder if I had a super power, would I use that power for the betterment of all people?
I know I enjoy watching or reading about characters like Harry Potter , Batman, The Green Lantern, and Wonder Woman to name a few, and I believe these stories try to work out this question while at the same time entertain us.