USB as a technology has undergone several revisions in its lifetime. The first generation operates at a rate of 12 Megabits per second (Mbps). USB 2.0 operates at 480 Mbps. Upcoming USB 3.0 operates at 5.0 Gbps. A Hi-Speed port is USB 2.0 or better. If the computer is older and only has full speed USB 1.0 ports, termed low speed in your message, USB 2.0 ports can be added by adapter cards, such as this
SIIG Low Profile PCI USB 2.0 Adapter. Cards are available in PCI, PCIe, Cardbus, or Expresscard format to match whatever bus format your computer uses.