Hi Avinash,
I have not used this myself but I believe that there are tools that help you migrate from PVCS to Subversion. Here is one link that you can try
http://www.polarion.com/products/svn/svn_importer.php
BTW - this all depends upon whether or you not you want to port over history which is usually not very useful.
Bob Aiello, Technical Editor, CM Crossroads