Difference between CurrentClockSpeed and MaxClockSpeed

Processors these days are fairly intelligent about what's required from them, especially in laptops. Just because a processor is 1.83Ghz, it might decide to save power (and heat) by running at a lower clock speed if the extra power is not required.

You can see this difference by going to your Windows Task manager. It's clearer in Vista and Windows 7, but the facts are still there in XP. You will see that your processor speed is listed twice. When my machine is running at full power, it says:

Intel(R) Core(TM)2 Duo CPU T7500 @ 2.20GHz 2.20GHz

However, when my battery gets low, it reads:

Intel(R) Core(TM)2 Duo CPU T7500 @ 2.20GHz 1.80GHz

So basically, that artical you linked to is correct. I would expect that MaxClockSpeed will always return the same value (in my case, 2.20GHz, because that's what's reported by the BIOS).

In regards to overclocking, an overclocked CPU's BIOS will return its theoretical maximum speed, so if you overclock a 2.0GHz to 2.4GHz, then it will report 2.4GHz.