DisplayHyperLink - Hyperlink URI

I've used the CreateTempFile and my content type is "application/vnd.ms-excel" and my partial Url is "mailingUrl" which is of type "string"

The next step, the DisplayHyperLink activity, requires a hyperlink URI and from the examples I've seen on the site, many have a combination of two

variables ie. hyperlinkUri  +  mailingUrl.

But if I'm allowing the user to select the link to download the excel file, would not the required hyperlink store a directory on your local drive, rather than opening up a webpage?

Also, am looking for commands that you can use with the RunExternalCommand, ie. open excel and display the file that was just created, but can't find any reference in the Silverlight Admin/Developers Guide.

Walter