Quicken is very easy to use, and is useful for keeping and organizing both business and personal financial records. Quickbooks is a little more expensive and difficult to set up and use, but is more “industrial strength”. I would guess that quicken would meet the needs of most teachers.
We use Microsoft Business Contact Manager, which integrates with Microsoft Outlook, for contact management. Again, this may be overkill for many teachers’ needs, but it comes included with certain versions of Microsoft office, and works great. If you are already using Outlook, I would recommend it.