The gap between Windows 8's and Windows 7's pre-launch adoption has widened in the last four months. (Data: Net Applications.)

The operating systems have had an equal opportunity to win hearts and minds: Microsoft delivered two early versions of each to the public. They also appear to be on the same shipping schedule. Windows 7 went on sale in October 2009, and although Microsoft has not yet set a release date for Windows 8, most experts expect that it will also launch in October.

If Microsoft watches these numbers -- and there's no reason to think it does not, since the company regularly cites Net Applications' data when it discusses Internet Explorer's browser share -- it must be disheartened by the comparisons.

Not only does Windows 8 compare unfavorably to Windows 7, but the gap between the two has widened. Two months ago Windows 8's share was half of Windows 7's three years before. Since then the difference between the editions has doubled, with Windows 8's June share only one-fourth of Windows 7's in that month of 2009.

Unlike post-launch share data, the early returns are not tainted with new PCs that come with an operating system. Rather, users chose to install the previews of Windows 7 and Windows 8, and thus the share figures represent a more accurate picture of customer interest in the upcoming operating system itself, not in the desire -- or need -- to acquire new hardware.