How do I disable a Nvidia 9600GT on MacBookPro 5.1?

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http://askubuntu.com – i finally put up a Dual Boot with Ubuntu and Lion on my old MacBookPro 5.1 As reported in many cases the discrete graphics card is turned on all the time consuming a lot of power and thus heating up the laptop. Since the discrete graphics card does not support the nvidia optimus technology, the corresponding packge nvidia-prime does not help in this case. Therefore my question is, how to manually disable the discrete graphics card Nvdidia 9600GT ? Preferably a 'switch-on-the-run' version, but a 'set-on-boot' would be totally fine! (HowTos)