Microsoft hopes to breathe new life into the weak PC market when it formally releases its new Windows 8 operating system this coming Friday. If you’re planning to upgrade, prepare to learn Windows all over again.

The latest version of the world’s leading computer operating system has got a radically different look, with colorful on-screen tiles in place of familiar icons, and new ways to open files and start programs. Morningstar analyst Andrew Lange expects the resulting learning curve to make companies think twice about switching. “It’s not going to be an overnight change, that’s for sure,” says Lange.

Gartner analyst Michael Silver expects the first adopters to be home users, and says businesses are likely to hold off at first.

Microsoft is pushing a common interface across its Windows phones, tablets and desktop PCs. Silver says a mouse will work, but the emphasis is on touchscreen “gestures,” by now familiar to users of iPads and Kindles. “If I want to turn a page on a document, then I flick my finger,” Silver explains. “That actually, eventually, should be easier for most folks than using a mouse.”

Still, Morningstar’s Lange concedes that, for some, the changes could be too much, too fast. While the new software has been getting positive reviews, he says, “at this stage, no one really quite knows how, exactly, it’s going to play out.”

During a conference call with analysts last week, even Microsoft’s chief financial officer Peter Klein wouldn’t offer any sales predictions, saying only, “We’ll see how it goes.”