I was tinkering around with sending files across a web site at work and found this article byparticularly useful.
It covers the setting of the Mime Type, changing the file name that comes across and forcing it to appear as a pop up.
Changing Mime type:
context.Response.ContentType = “application/vnd.ms-powerpoint”;
Force Pop up and changing file name:
Overall it was what I needed to get the job done