You can definitely import any number of Windows sticky notes using Notezilla
To know the format, you can first export some notes to comma separated or tab separated file format. Go to Notezilla
Notes Browser and select File->Export option to export.
You can then add your 2000 notes to same file and import back.
However, I would suggest that you do batch wise so that you don't waste time. You can do 100 notes first and then 500 notes etc.
Also, doing batch wise will help you to import notes into different folders (memoboards).