Opening files with default Windows application from within emacs

1. Evaluate the following elisp
2. Run dired (M-x dired)
3. Browse to directory and file

4. With point on file, pressing F3 will open the file based on the windows extension.

   (defun w32-browser (doc) (w32-shell-execute 1 doc))

   (eval-after-load "dired" '(define-key dired-mode-map [f3] (lambda () (interactive) (w32-browser (dired-replace-in-string "/" "\\" (dired-get-filename))))))

To extend on the 'org-open-file' proposal:

(defun my-dired-find-file (&optional prefix)
    (interactive "P")
    (if prefix
        (org-open-file (dired-get-file-for-visit) 'system)
      (dired-find-file)))

(define-key dired-mode-map "\r" 'my-dired-find-file)

Will let you open a file externally with `C-u RET'.

found at http://lists.gnu.org/archive/html/bug-gnu-emacs/2012-11/msg01069.html