Lpc2000

Hello,
This is more of a general question regarding using the SPI peripherals
with the LPC2000 chips.  I'm somewhat new to this form of serial
communications, so sorry for boring all you pros out there.  I'm
developing with the LPC2220 chip, and am actually using the SSP
peripheral, which, for all intents and purposes works just like an
SPI, but with a few extra options.  

My question is, if you're running the processor's SPI in slave mode,
do you still have to set up your clock speed in the SPI registers to
match the SCLK speed that the external master is giving?  Or does the
external SCLK pretty much just clock in everything into the
processor's SPI data registers for you and you don't have to worry
about the SCLK speed (on the processor side)?

Thanks so much in advance for your help.
Jeff.