I'm running now on a P3 500. It's a Slot 1, 100 FSB, 512KB. The maximum upgrade this older Intel mobo will accept is a P3 600. My question is what is the difference between a P3 600 processor rated at 256KB cache versus 512. I see that two versions are available and I'm wondering if they are compatible, and if there is a notable performance difference. The difference in price has me wondering. Thank you.