Microsoft announces this morning that Windows 7 is now 18 months old, and the software giant has now sold over 350 million licenses to the OS.

The momentum we’ve seen and continue to see with Windows 7 is incredible.

Number of licenses sold is one way of looking at market success. Customers having a positive and productive experience with Windows 7 is also an important measure. Analyst firms like IDC estimate that more than 90% of businesses are currently in progress with their Windows 7 migrations. And we’ve seen that companies who have deployed Windows 7 save an average of $140 per PC per year – showing a 131% return on investment in just more than 12 months.

We’ve done a lot in the last 18 months that improves upon the experience people have on their PCs with Windows 7. We launched Windows Live Wave 4 (which included Windows Live Essentials 2011 and enhancements to Hotmail), released the first service pack for Windows 7, and recently launched Internet Explorer 9. And we’re hard at work on further innovation for Windows. At CES this year we announced the next version of Windows will support System on a Chip (SoC) and last week at MIX11 we released the first platform preview to developers for Internet Explorer 10.

So this is big news, of course. I do sort of wish that Windows Live was on a more aggressive schedule, however. When you consider that Windows 8 will hit about 3 years after Windows 7, we’re officially at the half-way point between the two OSes now. So why is there no new Windows Live Essentials hitting right now or even an update to the current version? Wasn’t that the point of separating those applications from Windows? So they could be updated more quickly?

I don’t mean to be a wet blanket. I’m just wondering.