Thank you all for the suggestions, but my problem is still not resolved.
My OS still does not identify the CPU. It says "Unknown Processor Type" and the it is only running at 796 MHz when it should be running at 2.0GHz. I did try the Central Brain Identifier, but it did not bring any changes in the performance of my Athlon XP-M 2600. Besides, changing multiplier from the CBID is only temporary and I really do not believe it works. Is there anyway I can speed up my CPU by changing the BIOS settings??? I need help...a serious one.
CPU: AMD Athlon XP-M 2600, Socket A
Memory: 512MB PC133 SD-Ram
Motherboard: SiS 730a
BIOS: Phoenix Technologies, Ver 6.0