This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Presumably C:\Two already exists (perhaps it's actually the directory you wanted to move the file to), so you can't rename C:\One\sai.txt to that. Did you actually want to rename it to C:\Two\sai.txt? If so then do that.
I’ve looked at a lot of different solutions, and in my humble opinion Aspose is the way to go. Here’s the link: http://aspose.com