There is a difference between security issues related to various applications and security issues in the OS itself. If Aberdeen were honest, the counts would add up far differently. In Linux it is easy to turn off network services or applications revealed to have problems, without having to shutdown or reboot. The patch can be obtained and applied, and services restored, without reboot (usually). In Windows, you always have to shut it all down for reboot, even if it is running as a server, after security patches are applied. This means security of operations with Windows is ALWAYS affected. Security of operations of Unix based systems, like Linux, will always be less affected, due to the layering and seperation between OS, network services, and applications. Windows, with it's monolithic approach to everything can be automated by the web, creates a major security problems every time any exposure is found. Linux, when the OS actually has a problem, that problem is localized and containable. Patching it is hours or days away, many business processes remain possible, and the update is free of constantly changing EULAs and Microsoft-forced modifications and unexpected default resets of options.
You can keep your Windows...but be extremely cautious about security flaws. When Windows has a crack in the door, the whole house is exposed, for weeks and months. When Linux has a crack, a room might be entered...for a few hours or days. When the patch from Microsoft comes, it may gum up other stuff, and require you to give up more rights to your PC to Microsoft. Linux always leaves you in charge.