Windows 7 was released on October the 22 last year, and has since then managed to amass mostly positive reviews with many labelling it the operating system Windows Vista should have been.
"We're humbled and excited that people are responding so positively to Windows 7," Brandon LeBlanc said on the Microsoft Windows Team blog
"Our customers have made it the fastest selling operating system in history."
To put this milestone into perspective, Windows XP sold 17 million copies in its first two months, while Vista, Windows 7's predecessor, has been purchased just over 140 million times in total. The 90 million figure is up from the 60 million copies the company had sold at the end of the January quarter.
Unfortunately for Microsoft, however, it seems most of these 90 million licenses sold have been for home and non-commercial purposes.
"There will be an enterprise refresh cycle," Klein said when asked about the lack of uptake by commercial organisations.
"It's not precisely certain when that will happen and how fast it will happen. But as we've [Microsoft] been saying, specifically for the last several quarters, we expect it to happen this calendar year and go into next calendar year."
The problem most enterprise organisations face is non-compatibility with many older programs still in use by most large corporations. This time around though, Microsoft has attempted to combat these potential issues with 'Windows XP Mode,' that runs a virtual copy of XP using Microsoft's Virtual PC technology.
Windows 7 has been seen by many as the operating system which will finally takeover and replace Windows XP, which Microsoft has been desperate to kill-off and supersede.