ER positive and HER2 positive

Have IDC with 1.1 cm tumor Grade II, Stage II, ki-67 at 21% - also have ER positive tumor and HER2+++ - also have negative sentinel node but positive other node (ANOTHER node was negative). I have been reading alot about HER2 and it's pretty scary - does anyone know if the fact that I am ER+ and HER2+++ a good or bad thing - does the chemo for the HER2+++ and the tamoxifen for the ER+ work together or against each other? I am confused. I will ask my oncologist this week but don't start therapy until 07/09 and am trying to make sense of it all. just had lattisimus mastectomy and awaiting treatment. Thank you ladies - you are all my heroes. Cindy