The main board comes equipped with USB controllers. So it depends on the chipset and its specifications. If its a new system purchased in the last couple of years, it would most probably be a USB 2.0
USB 1.1 cannot be converted into USB 2 just like that. You would have to add a PCI slot offering you 2-4 USB ports at the rear of the cabinet or probably a IDE device fitting on the front disk bays on the cabinet. Not quite sure about the availability of the latter.
Approx cost for the PCI card would be around 1k. For accurate prices, refer ebay.in