 This study evaluates the effect of two medicines on COPD Chronic Obstructive Pulmonary Disease exacerbations. This study will last up to 56 weeks, and subjects will visit the clinic 10 times. Subjects will be given breathing tests and will record their breathing symptoms daily on diary cards. All study related medicines and medical examinations will be provided at no cost. The two drugs used in this study have been approved by FDA for use in patients with COPD. 