Sudir Nim gives the best option, but keep in mind, the "save" dialog box is a function of the browser, and not the server. How the browser behaves when any file is accessed is based on the configuration of the browser.
With Sudir Nim's suggestion, the server gives a "hint" to the browser (it's not telling it to save via content-disposition), but it's still up to the browser to determine what to do.
In preparing for battle I have always found that plans are useless, but planning is indispensable. -- Dwight D. Eisenhower