Suasan, you might want to check out Phanlanger
, a PHP Compiler for .Net.
After phpBB 3.0 RC1 is released I'm planning to merge it into an ASP.Net 2.0 application (VB.Net) and essentially use php ascx user controls for forum functionality. When I get it banged together I'll add it to the Open Source Projects code repository.
Don't expect it any sooner than a month after phpBB RC1 is released.