Despite receiving support from nearly all of its hardware partners, Microsoft's (NASDAQ: MSFT ) Windows 8 has yet to catch on as a tablet operating system. Last July, Microsoft took a $900 million writedown on its Surface tablet. Though sales have improved, Windows tablets remain largely in the minority -- IDC's most recent data shows Microsoft's operating system with just 3.4% of the global tablet market.But even that modest success could soon unravel. Both Apple (NASDAQ: AAPL ) and Samsung (NASDAQOTH: SSNLF ) appear poised to aggressively target the enterprise tablet market in 2014, perhaps the only market where Windows tablets have an...