Apple's market share is slipping: it accounted for nearly three-quarters ( 74.4%) of all online movie sales in 2009. Its competitors are taking a few bites here and there: Microsoft has increased its market share from 11.6% to 17.9%. It offers titles via the X-Box 360 and Microsoft Zune. Sony, which sells movies online through the PlayStation 3 player and select Sony Bravia HDTVs, has gone from 5.7 % to 7.2% in 2010. The rest of the bunch accounts collectively for 10.4% of the market, up from 8.3% in 2009--and that includes Wal-Mart's Vudu se