On Windows, it's Folder Options > File Types; on OS X, right or control-click on a file and there is an "open with ..." option which has a further option to "change all ...". Don't know about *nix or OS/2. Ha ha. -----Original Message----- On Behalf Of Randal Rust On 3/28/07, Erik Mattheis <gozz at gozz.com> wrote: > What you would be "validating" is whether the user has the mime type > correctly set up on their box, not anything about the file. OK, then that's what I need to know. How do I correctly set up the MIME type for Acrobat and Excel if I don't have the programs installed?