ARM III: Patients receive doxorubicin hydrochloride and cyclophosphamide as in arm I. Patients then receive paclitaxel IV over 1 hour and trastuzumab IV over 30-90 minutes beginning on day 1 of week 13 and continuing weekly for 12 courses. Patients then receive trastuzumab IV over 30 minutes beginning on day 1 of week 25 and continuing weekly for 40 courses in the absence of disease progression or unacceptable toxicity.