In this case the OP isn't even overclocking but is being given advice to disable a power saving feature. If you read the thread up until my post there was not even any mention that the computer will return to normal speed when under load. The other one hundred people who will reference a thread like this while googling would come away thinking they need to disable speedstep for their computer to run full speed.
As far as overclocking goes I think people should question the common stance on this. An overclocked system has even more to gain by running with speedstep by having lower idle temps. I'm not sure about the AMD's and running with cool n quiet but most of what I've come across in the forums suggest the newer Intel procs overclock just fine with speedstep. Like I previously said, if disabling it fixes a stability problem then fine but the goal should be to at least try to run with it on.
I'm not driving a Prius or voting for the green party but I am trying to use a little less energy. Shut off lights, enable speedstep, a few more PSI in the tires. I'm using less energy this year and sacrificing nothing in convenience.
Looking ahead it seams that power saving features will be stepped up in CPU's and GPU's. I hope we are not advocating disabling these features simply because it is conventional wisdom.