Statistics from NetApplications reveal 20 out of 10,000 computers are running a copy of Microsoft's Windows 8 previews. While these copies aren't intended to be run by the general public, the adoption rate of the Windows 8 preview releases seems to indicate that the new operating system won't be as popular as Windows 7 as the install rate is much lower than with 7:
The previews of these operating systems were not launched at the same time of year; the first Windows 7 preview was seven weeks earlier in the year than that of Windows 8. However it is still interesting to see the time comparison graph, even considering the one and a half month head start for Windows 7.
If the time line was adjusted to give both release previews a coinciding start date, then at four months after preview availability Windows 7 was three times more popular than Windows 8. Also is you look at the graph it doesn’t look like Windows 8 is catching up, the graph shows a divergence unfavourable to Windows 8.