Well as far as file uploading goes first let's deal with the timeout issue which can be a problem if a user is uploading a fairly large file (although perhaps you don't want the timeout increased too much because you DON'T want a user uploading a large file).

For pure ASP (i.e. non component) solutions (and I believe this would be true for component solutions too) can increase the timeout for the page:
' Script timeout in seconds for this page.
' (60 x 60 = 1 hour.)
Server.ScriptTimeout = 60 * 60

Also the Anonymous Internet user needs Change permission on the folder that a file is going to be uploaded to and actually Full Access might be better if you are later going to use the FileSystemObject to delete a file.

Here is a resource for letting the user upload a file which is something that was unfortunately not built into ASP:

ASP File Upload Using VBScript by John R. Lewis - 7/10/2000
http://www.aspzone.com/articles/john/aspUpload - http://www.aspzone.com/articles/john/aspUpload

And perhaps this might be interesting as far as downloading goes:

How do I prompt a "Save As" dialog for an accepted mime type?
http://www.aspfaq.com/show.asp?id=2161 - http://www.aspfaq.com/show.asp?id=2161