For the most part, the High Speed USB controller will be integrated right onto the motherboard of your system. You will sometimes run into this problem when upgrading to or installing a new version of XP, for sometimes it does not readily have the drivers available. What you have to do is to actually find out the motherboard that you have in your system, and download, or request the CD, that has the motherboard resources on it, in order to get Windows to install that particular controller. If you have a name brand computer, you should be able to contact the manufacturer to get the CD or download. However, if you have built the system, or someone else has built you the system, you will need the CD that came with the motherboard.
Older computers often do not have high-speed USB controllers. However, you can purchase these as PCI cards at any computer store. Shut the computer down and open up the computer's case. Next, slide the USB card into a free PCI slot on the computer's motherboard. Start the computer up and XP should detect the new controller. Insert any driver CD provided only if asked by XP - most don't require it.
Yes. If you have an empty PCI bus slot on the PC motherboard, you an install a PCI card which provides you 2 or 4 USB2.0 ports which are available at around $10. There are some combo cards which provide both USB and Firewire (1394 ports).