Margaret Sanger’s Disneyland - An easy chart of your birth control options has some information on the fertility awareness method.
Even if you've had your period for at least five years and it's pretty regular this is still a very difficult thing to master. I'm onto my fifth month of charting (I mark down my period, cervical mucus texture and basal body temperature every day)and I still couldn't tell you when I ovulate with any certainty. It takes a long time to get to the point where you can trust this method and even then it's much more useful for getting pregnant instead of preventing it, not to mention a 22% failure rate.
Condoms alone, if used consistently and correctly, will offer adequate protection. The most reliable form of protection is proper condom use paired with a hormonal birth control like Lunelle.
That doesn't mean you shouldn't give charting a shot; it's a really cool way to learn about your body. However, I'd think very careful and do a ton of research before using it as a method of birth control.
[This message has been edited by ookuotoe (edited 10-04-2002).]