Some have speculated that most enterprises may bypass Windows 8 altogether, because many companies are just now upgrading from Windows XP to Windows 7. Enterprises typically do desktop OS refreshes every three to five years, and sometimes wait even longer to embark on what is a very complex and costly upgrade process.

It also remains to be seen how enthusiastic tablet makers will be about making Windows 8 tablets, and ultimately how successful those devices will be in the market.

Some critics have questioned Microsoft's decision to include two user interfaces with Windows 8 -- the traditional Windows desktop and the new Metro interface, designed for touch-based screens -- because they feel the user experience could be clunky and problematic.

Microsoft, naturally, is doing its best to create excitement about Windows 8, and on Thursday touted improvements and additions in the Release Candidate, including new applications built by the company and some of its partners. Specifically, the Mail, Photos and People applications that debuted in Consumer Preview have been enhanced, the company said.

Among the "tens of thousands" of tweaks made since the Consumer Preview are more personalization options for the Start screen, better multimonitor support and new security features for parents to monitor and control their children's online and PC activities.