Krista,
I have listed a link to another thread on rib pain.
In order to take an AI, you must be in menopause. I have been taking Lupron shots to keep me in menopause since November of '05 so that I can take Arimidex. However, I was in a much different situation than you. DX at age 45, no more children planned. Be sure to discuss your desire to have more children with your onc and take this into consideration in your treatment plan.
http://her2support.org/vbulletin/showthread.php?t=31453