To be honest I don't think changing the past will affect you. If time is simply viewed as another point on a 4 dimensional plot, you'll change the past but the future will be changed. You, however, are considered part of the time you are in now, because that is where you are.
If you changed the past and it affected you, then it would change you. That change would therefore affect everything, including the changes you were making. This could involve you not changing anything at all, as in the case of you not being born at all and therefore not being able to affect the changes and therefore being born.
Check out the link I posted, it's very entertaining.
