Microsoft (MSFT) on Thursday took to New York City to announce availability of its brand new Windows operating system in more than 140 markets around the world. Windows 8 and Windows RT usher in the new face of Windows, a tile-based interface that combines shortcuts and widgets into tiles that can deliver live information to the user. Windows RT is a “lite” version of the platform compatible only with specially made applications, while Windows 8 combines Windows RT with classic Windows that is compatible with legacy and new x86 software. Windows 8 is available starting at just $39.99 for a limited time and upgrades from Windows 7 start at just $14.99. Microsoft’s debut tablet, the Surface, will launch tomorrow starting at $499.