csFileDownload Description:

This ASP component enables file downloads to be controlled from within a script. This allows code to be executed before and after downloading, which means password protection of individual files can be implemented easily. Records can be updated accurately because it is possible to detect if the download was completed or cancelled part-way through.
A built in access code generator is provided to produce access codes "on the fly", which can be verified before allowing a download.
Some file utilities are also included, such as Copy, Rename, Delete, and a single command to append a line to a text file.
There is a free trial available complete with full instructions.