Microsoft is on the cusp of a renaissance as it overhauls Windows both on the client and in the datacenter. It's no secret the company's core software platforms are under siege by Amazon Web Services LLC, Apple Inc., Google Inc. and VMware Inc. But Microsoft's day of reckoning is fast arriving as it prepares to deliver its response later this year. The imminent launch of Windows 8 (the most radically redesigned release of the client OS to date) and Windows Server 2012 (which is aimed at letting enterprises transition to cloud computing) will shape Microsoft's fortunes as it battles to convince consumers and IT pros alike that its best days aren't behind it. Critical to Microsoft's future is making sure it doesn't lose its footprint in the datacenter and its dominance on PCs or whatever client devices workers choose as alternatives.