Myth #1. There's so much discrimination in the computer field that women can't get ahead. That's not true. Yes, there's discrimination, but it makes women in the field stronger, not weaker. As a woman, you may have to work harder than the men who get unearned privileges. But there's a silver lining in that cloud. It will make you better at your work and more agile. If you find yourself in a job where the good old boys won't give you a chance, leave. The good news is that the hard work you did will make you qualified for many other jobs.
Myth #2. It's young, geeky, conceited guys who work in the computer field. This is partially true, but there are a lot of mature, non-geeky men and women also. Plus, the young smart-alecs can be funny, and they are trainable.
Myth #3. Heard from a parent: "Why should my daughter study computer science? She's already good with the computer." First of all, don't say "the computer." It dates you. :-) Kids these days are good with computers, whether it's Mac OS, Windows, Linux, or the mainframe that runs the cash registers where they sell lattes to overpaid executives who don't pay enough taxes to fund schools so your kid can get a better job. Computer science isn't about "using the computer." It's about creating the technology that makes computers function.
Myth #4. Women are motivated by social responsibility and helping people. The computer field isn't about helping people. Try telling that to Dawn Taylor, Ph.D. who works on brain-machine interfaces for prosthetics that restore movement for paralyzed people. Try telling that to Latanya Sweeney, Ph.D. who is dedicated to creating technologies and related policies with provable guarantees of privacy protection while allowing society to collect and share sensitive information for worthy purposes. Or take me. Please take me. :-) I got into computer networking not just because I love hardware, systems engineering, and network design. I got into it because it enables people around the world to communicate and collaborate. I didn't work at Cisco just because of good stock options. I worked there because Cisco understands that it's the human network that makes a difference.
Myth #5. All the jobs are moving to India, China, Kazakhstan, etc. Globalization is real. It's here to stay. But this is good for computer scientists! We build the technology that makes the post-geographic world possible. There are still lots of jobs in the US. However, maybe your job will be in Bangalore or Dubai for a few years. Cool! You may have colleagues in Brazil, Israel, Malaysia, Germany, the US, and countries you have never heard of. Way cool.
Finally, I would say, do what you love. If you were born a nerd, you'll know. You'll know you're happiest when solving problems, tinkering with devices, or writing software. You'll know that you enjoy configuring the family's home network, or fixing Grandpa's computer, or designing a code so you can communicate with friends in a way that non-friends won't understand. When you're doing what you should be doing, time goes by more quickly than expected. You feel energized and curious about what you're learning. Yes, there will be frustrations when your software/hardware won't do what it's supposed to do. But if you feel a sense of accomplishment when you work around those frustrations, you may be a nerd, and this is a good thing.
Artists see paintings in their heads. Musicians' brains play music. Social scientists analyze people. Natural athletes pick up sports right away. Perhaps you do some of these things too, but if you also solve logic problems in your head, and think in terms of numbers and databases and systems and communications, you may be a computer nerd. Join us! Please! We need you.