2210 OverClocking!?

Well, I was wondering about software OverClocking and I was wondering the danger of it. I want to here everyones thoughts on it because I am actually afraid to do it. My overclocked Casio after over 4 months of an overclock is finally getting problems. With the Casio it was 150MHz and NEC said 180MHz is the limit but someone has informed me that the X-Scale is 400MHz and can go up to 1GHz before damage. So what type of side effects would I need to worry about if I overclocked to 500MHz besides shorter battery life?