All Athlons were until a few months ago named on a power rating, not actual CPU speed rating. Since you didn't tell me the exact type of your processor i believe that it's the actual , normal speed of your CPU. But if it isn't then it's underclocked. To verify that go in the BIOS and see if the FSB is the correct value - 133MHz - sometimes it's at the default value of 100MHz. This can be changed from 2 locations:
1 - the JP4 jumper on the motherboard - 2-3 corresponds to 133MHz (of course you should change it only with the pc is disconnected from the mains)
2 - in BIOS go to Frequency/Voltage Control - CPU Host Clock and set it to 133.