Depending on the motherboard there may be a USB2 header on the board itself. Check the manual, if you've not got the manual post the make/model of board and someone will advise.
If you do have the header, you can buy a USB2 front-plate with up to 4 connections. The plate will fit in place of one of your front blanking covers normally used for an optical drive, the wires will then connect onto the header pins. j.