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.
Note, however, that you, the server-side web application, cannot write to arbitrary locations on the client-side (browser) hard drive. If you want the user to be able to save the file anywhere then you need to have the user (browser) download the file.
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