doofus32,
The resistor power rating is for average power. "RMS power" is a meaningless phrase, although you occasionally see it used in the literature, especially in audio publications. It comes from the fact that the RMS voltage is the voltage that will produce the same amount of power (heating) in a resistive load as a DC voltage of the same value. However the power we are talking about is the average power.
Regards,
Kral