There is usually no way to do what you describe. An exception to this is the environment for which you can integrate with a music and video hub. This will allow you, for example, to upload a movie and then play it the same way as if it were part of the zune collection, even if it was in IsolatedStorage.
, , WebBrowserTask. . , , Excel:
var wbt = new WebBrowserTask();
wbt.URL = "http://example.com/file.xlsx";
wbt.Show();
IsolStorage .