I am looking for a simple PIM / outliner (Windows XP compat.) similar to Treepad
(http://www.treepad.com) (tree structured, free flowing) that supports
the
following features...

1.  Use of 'tags' to manage large amounts of information.
For an example of tags, please see http://del.icio.us/recent and 
http://en.wikipedia.org/wiki/Tags

2. Built in spell-checker

3. Built in encryption

4. Ability to import Treepad files

The only example of an outliner with tags I have been able to find is
MyInfo (http://www.milenix.com/myinfo.php), however this product does
not appear to support spellchecking or built in encryption.