From personal experience, overclocking can damage components and everyone that overclocks should know this, I just had to eat it on a stick of Ram, so I personally decided to back off on my overclocking, so as not to damage any other components like my video card that cost more than my processor and M/B combined. If the manufacturer of the product can prove you've overclocked, your product warranty is gone. So if you've got plenty of moolah, to be constantly replacing components, then overclock to your hearts content, but be aware that you're pushing your components past what they were designed to do, and if you push it far enough it will break.
overclocking has the side effect of affecting your pci peripherals. my usb game pad became very aggreviated when i oc too much so i had to tone it down a little. when you oc the bclk to up the fsb to up the cpu frequency, things that depend on that bclk (133mhz system clock) will likely go out of spec. if these components had a robust design, then it may be able to handle the corner conditions, but many components will not like being out of spec.
<font color=green> there's more to life than increasing its speed -Ghandi</font color=green>