132/133, basically the same, I just say 133 because it requires less movement of my hand on the keyboard. I beleive that gamepark test the processors at 133, though, not that it really means anything.
66mhz is the official spec, this was changed from an original 40mhz, and most commercial games/software should run at that. That rule has been broken recently by JoyGP and GPCinema, I'm not sure how or why, but I don't beleive they should have included any speed above 133, too risky, despite the warnings that come with it.
Besides, when you go above 133, the battery life gets shorter and shorter. All emulators in my opinion, must have a 133mhz or less option. I don't think its a good idea for authors to get lazy, and hard code their emus at a higher spec.
Just remember that you are taking a serious risk if you clock it over 133, a very serious risk. It may seem to run fine, but the silicon in the chip will degrade a lot faster than normal. That happens in all CPUs, I managed to drastically lessen my old Duron 700s life by overclocking it more than I should have. I just ask for everyone to be careful and realise that if it fucks up, thats a good few hundred dollars down the drain for a few extra FPS.