http://netmarketshare.com/os-market-share.aspx?qprid=9

A seer you ain't. Let's all hop to Linux, because - oh, wait, it's less relevant each month. In fact, save for iOS and a few unnamed stragglers, they all lost a few pounds, just a few, to let the iOS in.

Must be a wording problem. Anyway, Crashdamage is right. DOS took decades to die off (BTW, the official time of death is 2000, but it lived on in various incarnations to date), and every now and then people jump ship to the next OS. Not as soon as they are released, because no matter how much you try, there's always SOME program that stops working. Each major release is work.

Vista was a joke and nobody will contradict this statement, Microsoft included. XP was the last good OS before 7, no wonder everyone sticks to it, especially since it runs fine on the latest 6-cores, with whatever RAM you can buy and all the drivers ever written. It's fine.

Here's a stat to ponder:

Windows XP (41.15%)
Windows 7 (26.35%)
Windows Vista (14.57%)
Mac OS X (7.07%)
iOS (iPhone) (2.20%)
Linux (1.65%)

7 has been around for 14 months (stats Feb 2011). Yes, the large majority, by (almost) any definition, runs XP. And given the fact that 1.5 years ago it was the only thing you could buy, there are a lot of systems out there that are too young to upgrade. Even so, it overtook Vista like it was going backwards (it is).

And this trend includes the period where everyone needed drivers, apps and compatibility checks, and doesn't include the EOL from MS (April 8, 2014).

Take pictures.