Final answer:
The user should be part of the Users group to create files, run applications, and install printers without excessive privileges.
Step-by-step explanation:
To create a user account on a Windows system that can create files, run applications, and install printers when the driver for the printer already exists on the computer, while having only the minimum rights necessary, the user should be part of the Users group. This group allows performing basic tasks such as running applications and using local and network printers. The Administrators group would have too many privileges, which is not necessary for the tasks mentioned. The Power Users group has been deprecated in the latest Windows versions and granted similar permissions as the Users group but with a few extra capabilities that are also unnecessary in this context. The Print Operators group is a domain group designed for managing printers on a Windows domain and would not be used in this scenario since we're discussing local printer installation where the driver already exists.