A 24-week Study to Evaluate the Efficacy and Safety of GSK573719/GW642444 125/25 mcg and 62.5/25mcg Inhalation Powder Compared With Placebo in Subjects With COPD

This is a 24-week, phase III multicenter, randomized, double-blind, placebo-controlled, parallel-group study. The study will have 9 scheduled visits and a telephone contact Follow-up visit one week following the end of study treatment. The study primary endpoint is -Clinic visit trough (pre-bronchodilator and pre-dose) FEV1 on Treatment Day 169 Trough FEV1 on Treatment Day 169 is defined as the mean of the FEV1 values obtained 23 and 24 hours after dosing on Treatment Day 168 (i.e. at the Week 24 visit). Secondary endpoints are; * Mean TDI focal score at Week 24 * Weighted mean clinic visit FEV1 over 0 to 6 hours post-dose at Visit 2 (Day 1) Eligible subjects will be randomised to GSK573719/GW642444 125/25mcg, GSK573719/GW642444 62.5/25mcg and placebo treatment groups in a 1:1:1 ratio such that of the planned 573 total number of randomised subjects, approximately 191 subjects will be randomised to each active treatment group and 191 subjects will be randomised to placebo. All treatments will be administered once daily in the morning by inhalation using a Novel Dry Powder Inhaler (NDPI). There will be a total of 9 study clinic visits conducted on an outpatient basis. Subjects who meet the eligibility criteria at Screening (Visit.1) will complete a 7 to 14 day Run-In period followed by a 24-week Treatment period. Clinic visits will be at screening, Randomisation (Day1), Day2, after 4, 8, 12, 16, and 24-weeks of treatment, and 1 day after the Week 24 Visit (also referred as Treatment Day 169). A Follow-Up contact for adverse event assessment will be conducted by telephone approximately 7 days after Visit 9 or the Early Withdrawal Visit. The total duration of subject participation, including Follow-up will be approximately 27 weeks. All subjects will be provided with albuterol/salbutamol for use on an "as-needed" basis throughout the Run-In and Study Treatment Periods. At screening, pre-bronchodilator spirometry will be performed followed by post-albuterol/salbut