Q: How do I open a .vnt file in O SX Mountain Lion 10.8.1

Several ways:

1. Drag the file onto the TextEdit icon.

2. Control-click on the icon and select Open with > Other..., then select TextEdit as the application to use

3. Start TextEdit, and then drag the icon for the file onto the TextEdit icon in the dock

You should be able to find most of what you need in the text, it's originally patterned after vCal format for events.

Anyway, I think there's a utility called MemoBlock that will read vNote data as pretty bits of text.