hmm let me get this right its all usb that are not working or is it just the front ones, if it was the front ones only then check the connections to the mobo inside.
If it is all the usb's check in the BIOS that they are turned on and if they are maybe try resetting bios , or check for latest bios vesion
EDIT>check event viewer as well this may tell you something
also did mobo come with disk if so it may have a diagnostic prigrame otherwise download ultimate boot cd http://www.ultimatebootcd.com/
this has tools to check mobo