Yes, PC133 is PC100 that has a higher max speed. There is no minimum speed, and RAM runs at whatever bus the motherboard chooses (the frequency is fixed by the board, not the RAM). There might be other requirements, but I'd try whatever's cheapest first and return it if that doesn't work.
<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>