Is it good to switch from c# to python?
Both are useful for different purposes.  C# is a pretty good all-rounder, python's dynamic nature makes it more suitable for RAD experiences such as site building.  
I don't think your career will suffer if you were competant in both.  To get going with Python consider an IDE with Python support such as Eclipse+PyDev or ActiveIDE's Komodo.  (I found a subscription to Safari Bookshelf online really invaluable too!)
Currently I am developing in the .Net environment using C# but I want to know whether it is worth learning python. I'm thinking of learning the Django framework. What is better?