An early version of Aero is highlighted, as well. Aero encompasses a new design philosophy that includes a translucent "glass" appearance of open windows as well as smoother transitions between windows. A re-designed start menu also is part of Aero.

An analyst described the December CTP as a progression toward the final version.

"It's just another release on the road to getting to a fully featured, complete version," said Michael Cherry, lead analyst at Directions on Microsoft, which is a research and analysis firm that independent of Microsoft.

"Certainly, they're starting to add some features that people are going to want to take some time to test such as BitLocker and Windows Defender," Cherry said.

Also featured in build 5270 are greater parental controls, such as the ability to limit the amount of time children can use a computer and integration with ratings boards that assess computer gaming content.