US STOCKS-Dow posts best month in 2011 but Microsoft drags

Dow rose 2.4 percent, the S&P 500 gained 2 percent and the Nasdaq advanced 1.9 percent. Merck & Co Inc (MRK.N Shares of Merck rose 0.45 percent to $35.95 while Chevron added 0.6 percent to $109.44. Both stocks are Dow components. [ID...