change filetype s edit with independent open with

Under Windows XP, I could go into Folder Options, select File Types, and use the "Advanced" option to select not only which program opens a file, but which (potentially different) program "edits" that file (when "edit" is selected using the right-click menu). So, for example, .htm could be set to open by default with Firefox but edit by default with Notepad.
I cannot find any way to achieve a similar result using Vista Beta 2. I can use the Default Programs control panel to associate files with ONE program, but only one program. Under the above example, I can theoretically use Internet Options to set Notepad as the default editor, but Vista apparently doesn't care and insists on "editing" with Word. But I would like to regain the kind of control I had generally (so, for example, I could "open" jpeg files with one program but "edit" them with another, etc.).
For what it's worth, I poked about in the Registry for a bit (HKEY_LOCAL_MACHINE\SOFTWARE\Classes), but Vista didn't seem to care very much. If there exist any other tricks, they lie beyond my Googling skills.
Am I missing something obvious (or, if I'm missing it, my ego hopes it's at least subtle), or is this functionality just plain missing? If so, I sincerely hope it's merely an artifact of this being a beta version of the OS.
If anyone can help, I'd really appreciate it.