Today I visit Microsoft website. When the page open completely Its ask for go to regular page or use new Beta. I select Beta. Its ask me to install Silverlight on my PC. There are 2 versions of Silverlight. One is 1.0 something and other one is 2 Beta. Which one I install ? And what they do ?

I have no idea. But let me try to explain it . Its same like if you install any program and its installed in activeX control. Silverlight is same thing like ActiveX that what i believe. When you use it and go to microsoft website, You see there extra feature like to access new page with 1 click like preview system.Use 1.0 version. Leave Beta . Because its Bugy.

heh here is the information about Microsoft Silverlight

Microsoft Silverlight is a programmable web browser plugin that enables features such as animation, vector graphics and audio-video playback that characterize rich Internet applications. Silverlight competes with technologies such as Adobe Flash, SVG, Adobe Flex, Adobe Shockwave, JavaFX, Curl and the JavaScript programming language.[1] Version 2.0, released October 2008, brings additional interactivity features and support for .NET languages and development tools.