Windows 7 is the subject of much happiness for Microsoft, but it can become a concern in the coming months. As the system has increased its user base, the occurrences of reported vulnerabilities in machines running the company's current system more Steve Ballmer also shoots up.
According to a study released by Microsoft for the second half of 2010, there was a 33% increase in the rate of infected machines running Windows 7 32-bit. In total, there is a ratio of 4 to 1,000 machines infected computers running Windows 7.
Windows 7 64-bit does better in this aspect. The same Microsoft found a proportion of infections of 2.5 machines with this flavor of Windows computers for every 1,000 checked. It may seem little, but it is worth remembering that Windows 7 is installed on millions of PCs around the world (and the trend is increasing more and more, while Microsoft follows the development of Windows 8 - unlikely name of product).
Among the newer Windows systems, XP with Service Pack 2 is still the most problematic. He appears first in the ranking of instances of Microsoft vulnerability, with 19.3 per 1,000 machines problematic. Then again Windows XP, this time with SP3, is 15.9 / 1,000 infected machines.
In general, one can observe that the 64-bit systems record a lower rate of infected machines. This fact is possibly due to two reasons: the peculiarities of 64-bit architecture, which tends to be more complex and less adoption of this technology by users. They are just kicking my own, however.