It very much depends on the motherboard you are using. The reset cmos jumper will erase it along with all other settings changes you may have made to the bios.
For better help we really need to know what motherboard, system, and bios you are using.
thank you for the reply..my motherboard is ECS EliteGroup 915-A which supports intel 775...could this help?and i've heard that there is a software that can help to clear the BIOS password...is this true?