EXS 24 Logic Sampler Users Group

I'm curious to know whether or not anyone has configured an Apple machine
that can approach the power of PC/Gigastudio setups using the new EXS Giga
import and hd streaming.  I do MIDI-orchestral stuff and am mac-based, so
the thought of having multiple tracks of sumptuous Giga-libraries running on
a mac has me foaming at the chops...

Are the current crop of G4 machines powerful enough to realistically pull
this type of processing off?  Or are we a generation or two away from having
the power available on the mac side to do this?  If you're doing this now,
any tips as far as hardware/software configuring?

Not trying to ruffle any feathers here--this is a serious issue for me.

Thanks,

Tim