As far as I can tell, it is a widely known (and much wept over) fact that NVidia's highly touted (by them) overclocking utility - nTune - simply does not work with Windows Vista. Yes, it will overclock your GPU, but you cannot save a profile, thus you have to overclock again each session.
Why doesn't NVidia fix this? They have to know the software they brag about on their support site simply does not work - yet they continue to promote it.
Maybe the line on their website should be, "Download nTune! It looks real pretty! (oh, and BTW, it doesn't work - sorry...)"