Using the HTTPResponse class instead of a popup

In the past I have always used a popup window to create an excel export of some html data using something like....

Response.ContentType = "application/vnd.ms-excel"

Response.AddHeader("content-disposition", "attachment; filename=hadeno.xls ")

Response.write("Hello World")

Could someone tell me if there is a way in which i can do the came as part of an Ajax call. If i do the above i just get 'Hello World' rendered on the screen. I assume thats because i am using the same response object that is used to service the ajax request - so i started playing arounbd w ...