Ok, this might not be an issue for all systems, but few (like mine )
Here is the problem. I will explain with screenshots
First, the good one which is from Vista Control Panel,
And the bad one which is built using Visual Studio 2005/2008 beta 2 and also with Expression Blend,the result is same
Can you notice the tick mark above, how bad it looks
To solve the above problem, we have to set the rendering option for CheckBox as below,
So, if anybody are stuck with this problem, do not forget to set the RenderOptions for your CheckBox !