Quote from Pampersit does not work for vista 64bit : <
Huh? Stop posting nonsense, the nvidia PS plugin always worked on xp64.
Satyre, the problem you're having is really weird. Installing that plugin could not be easier, you don't even need to go to the PS dir and paste stuff in there, just downloading the DDS plugin installer, next next next and it should be it.
I dunno, try reistalling PS and install everything again, this time without overcomplicate stuff. If all else fails, I'm sure you can e-mail nvidial support and ask for help, or even better head over to their forums or check their FAQ section.