C# - Print Letter And Forms With Mail Merged Data?

I currently have a customer that needs to print forms, letters, etc.. for their clients. I wrote an asp.net application that my customer uses to run their business plus a console app that does the printing of these forms and letters. However, even though the print program works fine, I am not happy with it. I have these rtf templates that have tags such as <> that I replace with the correct client information by bringing in the template and doing a replace.

I have recently written a program that does a mail merge using Word Interop and it works well but I want to make sure this is the right way to go. I orignally put it in a windows app but just recently experimented putting it in an asp.net page but when I deployed it to the web server, I got some errors. I am not really in favor of doing this in an asp.net page but on the flip side, I am not really excited about deploying a windows app to the staff workstations.

If you had a small business customer with about 6 staff members who need to print forms, letters, etc... and merging the letters with their client data, what would you do. I have an IIS server, SQL server in house and full access to the domain.