Tracking file downloads

Hi I would like to know any ideas on tackling the following: I would like to have people give me their details via a form and then allow them to download files from the server, and I would also like to keep track/record of the files that are downloaded. The record doesn't need to be kept, just e-mailed to the admin as soon as it is done and the user exits the site. I guess this would be the perfect example for using sessions? Unfortunately I am not too hot on sessions, so any advise/help will be appreciated. Thanks