Massachusetts has a regulatory requirement to protect certain types of personal information, including social security number (SSN), driver's license number, financial account number, and personal credit card numbers. MIT has coined the term PIRN - Personal Information Requiring Notification. If this data is exposed, business entities in MA must notify the affected individuals. Since the first step in protecting PIRN is knowing whether you have it, it can be helpful to have a tool, such as Spirion (formerly Identity Finder), that locates such information on your computer.
Most people are aware of at least some confidential data on their computers. You can remove the confidential data at any time - you don't need to wait to install Identity Finder and do a scan to do so. But you should also take the time to scan your computer, especially if you've got years' worth of data on it or inherited it from a previous user.