Two months after its debut, Windows 8 is still struggling to make an impact. The adoption rate of Windows 8 is poor and probably the slowest in Microsoft's recent history.

The adoption of Windows 8 is way behind that of Windows 7. However, new evidence suggests that it is even trailing way behind Windows Vista in terms of adoption.

Microsoft's Windows 8 has online usage shares of less than 1.6 percent of all Windows systems through Dec. 22, according to a report by Web research firm Net Application. Released publicly on Oct. 26, Microsoft's latest desktop OS had online usage share of 1.2 percent in November.

The slow uptake of Windows 8 is a troubling sign for the software giant. Windows Vista, released in 2007, showed up on 2.2 percent of all Windows Desktop and Laptop PCs in the same time period. Vista is termed a failure for Microsoft as its adoption was lower than both its successor, Windows 7, and its predecessor, Windows XP. Windows Vista gained its peak in fall 2009 with a usage share of over 20 percent of all Windows machines.

Microsoft said in late November that it sold 40 million Windows 8 licenses. However, Microsoft's OEM partners cautioned that the uptake of Windows 8 is significantly slower than their predictions.

The overall decline in PC sales in 2012 due to the recent shift of users towards mobile devices like smartphones and tablets also seem to aggravate Microsoft's windows 8 sales fortunes. Additionally, it is also unclear how many of these 40 million Windows 8 licenses were for brand new products against software upgrades by users on previously-owned systems.

Net Application measures OS usage shares by recording data from 40,000 Web sites the analytics firm monitors for its clients. It records operating systems and version of the machines of site visitors. The results are accurate, but Net Application did leave out the last week of December, which is the most precious time for shoppers as well as retailers.

After the holiday season, the figures may change drastically. However, it is still unknown whether the touch-centric OS can start a revolutionary switch to touch desktops and laptops or it would end as a rare Windows failure like Vista.

What do you think about Windows 8? Leave your comments below.