Because this thread is written in english language, I'll answer in english too:
WMI would be another way, but via the CPUID instruction you have the direct
access to the CPU.
WMI gets some details from Windows, but that in a more general way. One advantage of the CPUID instruction is that you have special functions e.g. for the Intel Core2 processors or AMD Phenom processors, which aren't detectable in detail via
WMI.
WMI and the CPUID instructrion are both very good documented. There is no disadvantage here.
To create a general information tool,
WMI could be the first choice. But for a specific tool (and I believe he does develop such one) you need to
access the CPU directly. Or do you believe that programs like CPU-Z, HWInfo32 or Everest detect their CPU data based upon
WMI ? I don't think so.