You can't hide the link to the file directly; after all the browser needs to know which fie to download.
You could clear the status bar when the mouse hovers over the link so you can't directly see what file it is linking to. However, a simple right-click on the link, or View Source will reveal the link anyways.....
A better alternative might be to have a generic download page, like Download.asp that accepts the Id of a file users can download. Inside that file, look at the Id, find the related file and stream it to a browser. Take a look here for some ideas on how to do this:
http://Imar.Spaanjaars.Com/QuickDocId.aspx?QUICKDOC=189
This still doesn't really hide the file name though. Download.asp?Id=123 will always get you the same file though....
Imar
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Imar Spaanjaars
Everyone is unique, except for me.