CPU frequency scaling unsupported on Q6600

Hey! I've just installed Jaunty 9.04 and I can't get frequency scaling working on my CPU: Intel Q6600.
I get the following error with the Gnome applet CPU Frequency Scaling Monitor:

Quote:

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You will not be able to modify the frequency of your machine.
Your machine may be misconfigured or not have hardware support
for CPU frequency scaling.

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On Slackware I use to load a module acpi_cpufreq but it seems this is not applicable to my kernel,
Linux core 2.6.28-15-generic #52-Ubuntu SMP, probably because this is built in.

Any ideas? Thanks.