An EssentialPIM type of application

Isn't that what Keepass Portable is used for? At least that is what I use it for.

EssentialPIM is a full Personal Information Manager, simlar to Palm Desktop, with ToDo, Notes, Calendar and Addressbook, available in both paid and freeware versions. Actually, there is a portable version on the author's website ( http://www.essentialpim.com/ ). If we ever get a portable KDE or Gnome on Windows (the original needs to be released for Windows), either has an included PIM that would serve well. Some time ago, John released a add-on that allowed you to directly start the Thunderbird addressbook and the portable Sunbird calendar is also available here, which do a good job of supporting these needs. There may be other apps, like Keepass that provide other related functionality. There are other apps available for ToDo and Notes, for example.

Good luck with finding a good combination for your use.