First off, how old are you? How old is your boyfriend? In Ohio, the age of consent is 16. Basically, after you and your parter have reached that age, by law you can consent to sexual activity. Before that, depeneding on the age differences of you and your parter, he can be charged with a sex crime, and that's not a pretty picture.
I applaud you for wanting to discuss this with your parents. It will make things easier down the road.
First, I'd understand why they feel the way they do. Is that what they did? Is that what they were taught as children? Are they religious, and this is part of their teachings?
Next, I suggest you print out, read, and understand Margerat Sanger's Disneyland, our article that breaks down all the different types of birth control, their success rates, and their side effects, if any. Also, read and print out Your First Gynecologist's Visit, because if you're sexually active you should be seeing one for testing and to make sure all's well (also if you want hormonal birth control).
In addition, these articles will help you a great deal:
*Safe, Sound...And Sexy
*First Intercourse 101
*Ready or Not Checklist
Read them, and bring them with you when you talk to your parents. You're taking responsibility to prepare yourself. Speak in a calm manner. Explain why it is you want to do this. Assure them that you're taking precautions (as you read in the articles). You want to do this. But remember, being demanding won't help. If something does happen, you'll want your parents in your corner, so to speak.
Act mature, speak well, be responsible. And good luck!