ARM II: Patients receive paclitaxel IV once weekly and trastuzumab IV once weekly for 12 weeks. Beginning 7 days after completion of paclitaxel and trastuzumab, patients receive FEC comprising fluoroucacil IV, epirubicin IV, and cyclophosphamide IV on day 1. Treatment repeats every 21 days for 4 courses. Patients also receive trastuzumab IV once weekly for an additional 12 weeks. Within 6 weeks after completion of FEC and trastuzumab, patients undergo surgery. Beginning 3-4 weeks after surgery, patients receive trastuzumab as in arm I.