This document summarizes a study analyzing Twitter sentiment about the release of Windows 10 from July 28, 2015 to August 5, 2015. The study used machine learning techniques including logistic regression, decision trees, and random forests to predict sentiment polarity from tweets. Key factors found to influence polarity included the number of days since release, tweet length, and whether the Twitter user was a seasoned or new user. The study found sentiment shifted from positive to negative later in the sample period. It recommends Microsoft continue positive branding post-release and target influential, seasoned Twitter users.