Current Top 7 Operating Systems by Internet usage.

Based on current trends we will see the standings shown below from June 2013.
Windows 8 has leapfrogged Windows Vista and Apples OSX to sit behind Windows XP.

As XP now enjoys only extended support and each new computer system ships with Windows 8 we can expect XP to drop to the number 3 spot in the future.
 
The debate as to whether Windows 8 will ever see widespread use within industry will continue until it does and inevitably eventually occupies the number one spot ahead of Windows 7.

1. Windows 7
2. Windows XP
3. Windows 8
4. Mac OSX
5. Windows Vista
6. iOS
7. Linux