Visitors OS variation on my blog

Today I am quite curious about my visitors Operating System. You know I have add a tracker on my blog. I took that free visitors tracker from Sitemeter. When I am going checking to know about the operating system of my visitor blog. I got confused with two type of information.

Sitemeter said that most of my blog visitors using Linus.
But blogger.com blog's default (newly activated) Stats saying that my major visitors are using Windows operating system. Look at the images below:SiteMeter says that my blog visitors are mostly using Linux operating system. They are 46.2 % within all visitor.
But Blogger.com default Stats telling me that my visitors are coming from mainly Windows operating system. They are 56 %. What a contradictory problem! I am not sure which is correct.