XL,
That in itself is an advantage. Saves much thermal stress on your cpu due to thermal cycling and keeps your cpu core and case temperature more constant. Plus rc5, along with other distributed computing projects, is a good test of system stability. Burns in your cpu and proves that it can run stably at the desired speed, or not. It also makes good uses of otherwise wasted cpu cycles since, to quote someone whose name I cannot remember (with apologies) "Windows 9X notes when the CPU is idle and instructs it to process looping 'garbage' instructions" anyway. Monitoring your keyrate also allows you to identify underlying processes that might be using cpu cycles and other resources (e.g. viruses, worms & trojans) with a high priority and therefore substantially hindering your computing performance (unlike, for example, rc5 which, at idle priority, almost never interferes with your applications). RC5 has even been used to locate deficient cables in networking environment since the expected performance can be monitored.
If you ever want to give it a try, just PM me and I can have you cracking in less than 2 minutes. If you don't like it later, you only need to delete the rc5 folder to uninstall the client.
Maybe I'm Amazed (Paul McCartney)