The thing is, the pill becomes more effective as you use it longer, as long as you take it daily, and the particular pills fits will with your body chemistry. Many women have to try different brands of bc pills because they can cause adverse effects when attempting to regulate the body (as every woman is different... duh.) But, most women find that the many upsides of the pill (aka scheduled periods, reducing cramps, helping the skin, increasing breast size, and of course preventing babies) are the reason to take them. Doubling up is a good idea, but it seems to me that if a woman has been on the pill consistantly for years, and is very good about taking it and has one that suits her, there's not much of a need.
Now some stuff you all should of learned back in highschool about condoms. Condoms, when used correctly, are 95% effective. Unfortunately the percentage of sexually active people that use them correctly is so low, that the actual average effectiveness of a condom is down around 80%. Here's another point: If your computer screen is the size of a sperm, that means most std's are the size of your wallet, and it would mean that the HIV virus is the size of one pixel on your screen. Now if a single sperm can get through a condom (and they can, especially the "extra sensitive" kind), then std's and HIV have a much greater chance of getting through. So always get checked and make sure your partner has been too.
Anyway... that's all I get from my 10th grade health class.
I'm drowning in assholes.