(defun 4spaces (beginning end)
  "add 4 spaces to a block,
good for code markup in various wiki/blogs"
  (interactive "r")
  (save-excursion
    (goto-char beginning)
    (while (re-search-forward "\\(^\\)" end t) ;working!
      (replace-match "    "))))


but when I try to indent something like this:

kajds
kadsj
kadsj

it ends up indenting all but the last line, like so:

    kajds
    kadsj
kadsj