It seems that Google Analytics is not reporting Windows 7 users properly. According to the stats for my blog I’m getting an increasing number of people browsing my blog from Windows NT.
I would guess that the operating system is self identifying as Windows NT 7.0 which is why Google Analytics is putting the visits in the NT bucket, but Windows hasn’t been called NT (at least in a marketing sense) since Windows NT 4.0. After that it became Windows 2000* (which Google Analytics is identifying), then XP, Vista and now Windows 7.
* Admittedly with the tag line “Built on NT Technology”