Go to Yahoo and join the TsDoItYourselfHormones group to find out some information.
I do have to warn you from first hand experience with estrogen:
You will lose upper body strength.
Your male functionality will not be as strong and some males on estrogen get impotent.
In addition to breast growth you will see fat redistribution. Your face will look more feminine.
Also don't expect quick breast growth. I have been on M2F HRT with estrogen and a testosterone inhibitor for a year and I am just getting B cup breasts.
In short, you have to accept the fact that long term you will become like a woman, and not just in terms of breast growth. Just like genetic or natal women your breast development could be a lot or it could be slight. It depends on your genetics.
However after saying all this I am a lot calmer.
John