hi sivakl_2001,
As you have VS 2008 as well as vs 2008 sp1 already installed in your system then now install Microsoft® Silverlight™ 2 Tools for Visual Studio 2008 SP1 and it can be found here .
After complition of the installation you can install microsoft expression blend . This is a very handy tool for silverlight designning.
Using this tool you can create animations easily .
So install Microsoft Expression Blend 2 and then istall the services pack for Exression blend.
Now you are done to start exploring silverlight.