<< I believe the K7S5A has temperature monitoring and Fan-speed monitoring, but can you set it to shut down if the CPU temp goes too high? >>
You can't do it from the BIOS (at least, I've seen no way). You can install windows software that will throttle the CPU, or even shut down the system, if temperatures exceed a setpoint. Can't say what Linux options exist -- rain may work. In the windows category, there are several options. I use CPUCool for FSB overclocking and monitoring, but I'm not sure how well its cooling feature works with this chipset.