You should identify the list of modules loaded with
lsmod command and verify whether the intended module has been loaded or not. Do it with sudo or as root and verify.
Can you check in from BIOS if there is anything you could do related to speedstep_centrino. Recently, speedstep-centrino module is deprecated in favor of acpi-cpufreq.
Can you check whats in the files here? Just a paste would do.
Also, the entire content of /proc/cpuinfo.
BTW, about speedstep_centrino, here is what I found from net sources
Generally, SpeedStep will run at full speed while connected to AC, but drop to a slower speed on battery to save power. This can also be modified in the Power Management options so the system runs at full speed even on Battery.
Depending on your Power settings, the CPU may drop to a slower speed even on AC while it's idle (not really working hard), once you need the computing power, it'll automatically jump back up.
Putting your Power Management option to ALWAYS ON, will have the CPU run at full speed always on AC and battery.
More from intel article at http://software.intel.com/en-us/articles/enhanced-intel-speedstepr-technology-and-demand-based-switching-on-linux/