Microsoft on Tuesday announced that it has sold 40 million Windows 8 licenses since the system's release last month.

Windows CFO Tami Reller shared the news yesterday at the Credit Suisse 2012 Annual Technology Conference. "The journey is just beginning, but I am pleased to announce today that we have sold 40 million Windows 8 licenses so far," she said.

In a followup blog post, Microsoft said "Windows 8 is outpacing Windows 7 in terms of upgrades. We built Windows 8 to work great on existing Windows 7 PCs. And we also set out to make upgrading from Windows 7 to Windows 8 super easy."

More than five years ago, when Microsoft unleashed Windows Vista, the company said it sold 20 million licenses during its first month. "While it's very early in the product lifecycle, we are setting a foundation for Windows Vista to become the fastest-adopted version of Windows ever," Bill Veghte, a former Windows exec now at HP, said at the time.

Windows XP sold just over 17 million licenses after two months, Microsoft said in 2002.

PC Magazine