From my testing I have come to the conclusion that with Vista SP1 the TLB-fix is enabled all the time regardless of BIOS-setting. So the fix is probably included with SP1, or at least some earlier hotfix for Vista, as it was not always enabled. So it seems that doing it via software is the only option for it.

AOD seems to disable the fix only for the first core at "red" setting. At "yellow" or "green" the fix seems to be enabled for all cores.

sam2008: I believe this program of yours needs to be run every time Windows starts up. Am I right? So if I were to make it run at startup, I would always have TLB-fix disabled?