I have a basic webpage that has a couple links that users can go
to download certain document viewers. If the client has not
downloaded the viewer, it prompts them to download it and if it
already have been downloaded then it goes directly to the login
page for the software that uses that type of viewer.  The
problem is... that users don't always know if they have
downloaded it before and click on the link to download it. If it
already has been downloaded it takes them directly to that login
screen. They don't want them to go directly to the logon screen
at that point. They want them to do a check first to see if the
file(s) exist and if they do take them to a different page where
it tells them they already have the viewer installed. How would
I write the code that would check the PC that the user is on to
see if the file exists and if it does redirect them to another
page and is that possible to be checking files on the user's own
pc - is there some security implications?  Any help or advise
would be appreci