[antialiasis]

In order to use the user notes this way, you would necessarily be unable to also use them as they were intended (i.e. as a way for other users, often moderators, to comment on this user). Additionally user notes are a pain to get to, as in order to post or view them you need to view your own profile (something that requires you to either find one of your own posts, scroll down to the users online list and find yourself there, or use the quick links menu) and then click a further link from there, while to get to the notepad you only need one click in a very straightforward place. Of course you are free to use the user notes as a way for users to keep their own personal notepad, but this does have quite a few advantages provided that you are willing to install hacks on your board, which of course not all administrators are.

Personally, if I were unwilling to install hacks and wanted to achieve this effect through the default vBulletin features, I would rather simply use the suggestion posted on page three about adding a private profile field than start messing around with the user notes. Both are less accessible than the notepad, however.