GW572016 for Treatment of Refractory Metastatic Breast Cancer Paclitaxel With or Without GW572016 as First Line Therapy for Women With Advanced or Metastatic Breast Cancer Study Comparing GW572016 and Letrozole Versus Letrozole in Subjects With Advanced or Metastatic Breast Cancer Capecitabine (Xeloda) With Or Without GW572016 For Women With Refractory Advanced or Metastatic Breast Cancer GW572016, An Oral Drug For Women With Refractory Metastatic Breast Cancer After First-line Or Second-line Herceptin