Splitting audio into frequency bands for spectrum analysis

I'm in the process of building a basic metering plugin consisting of a goniometer and a spectrum analyzer similar to Logic Pro's Multimeter (see below).

http://documentation.apple.com/en/logicstudio/effects/index.html#chapter=8%26section=4%26tasks=true

My question is how will i go about splitting the incoming audio signal into frequency bands, and what is best to use for displaying such a thing?

i have included my patch, which so far includes some rough ideas for what i thought may be needed.

thanks