I have a ecs pm800-m2 mb with a 2.4 celeron processor. There is a setting in the bios (phoenix award bios) under frequency/voltage control called CPU Clock. I have the choice of anywhere from 133-166. Those numbers do not make sense to me and I don't KNOW what i should choose. My mb supports 533 or 800  fsb speed  and the processor has 533 fsb. If anyone could shed some light on this I would be grateful.Those settings are for overclocking the CPU.  Is this something you really want to do?  If yes, then do some research on the subject.

The default setting is 100 (100 x 4 = 400 bus speed).   400 x 5.5 cpu multiplier = 2200 MHz
CPU multiplier is fixed and cannot be changed.

100-133 FSB supports PC2100 memory.  If you try to overclock, you need faster memory.  If you have PC2700 memory, you can PUSH FSB to 166 and memory will still work.

I have 512 of PC 3200. does that mean that I can change it to a rate higher than 133?Start reading:  http://www.hwupgrade.com/overclock/cpu/index.html