I also got "into" Sci Fi because of Star Wars. I thought it was great when I was younger; they were always my favorite movies to watch when I had to stay home sick. Which was fine with my mom because she's in love with Harrison Ford. But that may be another discussion... Some of the books that I've read that could be categorized as SF are Ender's Game, which is an all time favorite of mine, 1984, A Wrinkle in Time, Hitchhiker's Guide to the Galaxy, Frankenstein, and His Dark Materials trilogy.
I think a definition of sci fi, aside from the "what if" factor that seems to be prevalent throughout these posts and our class discussion the other day, is fiction about how we interact in a world that has been dramatically effected by some type of scientific development.
I previously mentioned in my post Mary Shelley's Frankenstein. Interestingly enough I'm taking a course this semester on Post-humanism and one of our required texts is Frankenstein. There have been all sorts of criticisms and analyses published concerning it and how it ties into Post-humanism, etc. Two of these authors are N. Katherine Hayles and Elaine L. Graham. In Hayles's introduction she writes about the Turing test which is sometimes called the "Imitation Game." (Sorry to those of you for whom this information is a repeat.. which it may be all of you). Turing, a mathematician, devised this game to test when artificial intelligence had reached human intelligence. A human would go into a room where there was just a computer terminal and talk through the computer to someone. During phase one, the person would have to figure out if they were talking to a man or a woman by asking questions and they would be trying to mislead them. During phase two, the person would have to decide whether they were talking to a computer or a human being, both of whom would be trying to convince them that they were speaking to a human. If the computer succeeded, according to Turing, then artificial intelligence was equal to if not greater than human intelligence. Hayles argues however that as soon as you enter that room you deprive yourself of your senses and desires and needs, the things that are quintessentially human, and by entering into that room you have made yourself post-human.
One of the definitions on Wikipedia for post humanism is: a cultural direction which strives to move beyond archaic concepts of "human nature" to develop ones which constantly adapt to contemporary technoscientific knowledge. The posthuman is traditionally a concept that comes from Science Fiction, futurology, contemporary art, and philosophy. (Again, wiki). I just thought that it was a pretty awesome tie-in as I sat here reading my Post Humanism homework for tomorrow morning!