There are three generations of USB, which is something most people don't know.
The original was USB 1.0, designed for low bandwidth devices like mice, keyboards, and printers. Then came USB 1.1, which increased the speed roughly 10 fold to make it work with early digital cameras and other higher bandwidth devices. Then came USB 2.0, which increased the bandwidth just shy of 500X that of USB 1.0.
While each successive generation is backwards compatible, there's no forward compatibility. A USB 1.0 or 1.1 controller cannot be made into a 2.0 controller. You have to either buy a new motherboard or get a USB 2.0 PCI card. The PCI card won't be as fast, having to share the total PCI bus bandwidth of approximately 3.3Gb/s. A single USB 2.0 port is capable of 480Mbps, so you can do the math.
I've just connected an external 7200 rpm hard drive to my computer. However, a message advises me that the device is a high-speed device but is connected to a low-speed bus. and will function at a reduced speed, and suggests that I disconnect from the bus being used and reconnect to a high speed root hub, of which I have 6. I can't locate the information for doing this within the Help Centre. I'd be grateful for a solution to this problem.