Rain is a CPU cooler program. Originally designed as tool for the serious overclocker, this is a cooler program with no frills or extras. It doesn't need them. Rain issues the HLT (halt) command during periods of inactivity and the processor remains cooler because of it. Plain and simple. The benefits of running a cooler CPU are that it reduces power consumption, can extend laptop battery life, and prevents CPU heat related freezes and lockups. More important, it can prolong the life of your PC. NOTES: Windows NT/2000/XP don't need CPU cooling programs that execute HLT instructions (such as Rain) because they already comes with an option to execute HLT instructions when the CPU is idle.