Some additional Information for other users who might have the same question.
>After about an hour of Googling, I still don't understand the relationship between Processor Expert and the Kinetis SDK. Can
>someone explain it to me, or point me to some existing explanation that I've missed? Are they two different ways of
>accessing peripherals? Or are they used together?
The PE and KSDK are different things.
The KSDK provides you with functions (Drivers and HAL) to acces the Hardware of your device (like i/o, adc, dma, power modes, etc).
PE provides you with a nice graphical interface to configure and use the different functions to acces the Hardware of your device. The "components" can come from the KSDK or from Kinetis (PE) or from external sources (like other developers, see mcuoneclipse).
My personal favorite is to use the PE without KSDK, and then use the logical device Drivers (ldd). Freescale recomends using the KSDK drivers.