Considering the necessity for modern and high-speed internet connectivity, using a network interface card that fits in a Peripheral Component Interconnect Express slot is the best option. This interface supports a higher data transfer rate than its predecessors, making it the most suitable choice for new installations that demand enhanced network performance. An older expansion slot type, while possible to use, would not offer comparable speed and efficiency. External adapters like USB-to-network may not provide the stable and fast connection required for a workstation that is consistently connected to an intranet.