This study will involve the use of a new compound, GW642444 that is being developed for the treatment of asthma and chronic obstructive pulmonary disease (COPD). It works by acting on cells in the lungs, causing some of the muscles around the lungs to relax and open up better (bronchodilation), making breathing easier. When a medicine is made into a form ready to be given to patients, the active ingredient is often prepared in the form of a salt, and inactive ingredients (excipients) are often added. Inactive ingredients might be used to help a medicine work better, to make it easier to produce the medicine, or to make it easier to get an accurate dose of medicine. In previous studies the study drug has been given as a dry powder in the form of either the 'H' salt (with the excipient lactose), or in the form of the 'M' salt (with the excipients lactose and cellobiose octaacetate). In this study the 'M' salt form of the study drug has been prepared with lactose and a new excipient called magnesium stearate (instead of cellobiose octaacetate). Participants in this study will receive both the 'H' salt (GW642444H) and the new 'M' salt (GW642444M) containing magnesium stearate. This study will be the first time the new 'M' salt form of the study drug will be given to COPD patients.