EXS 24 Logic Sampler Users Group

Hey,
  I am just upgrading to logic Pro 7 from Platinum 5.5.1,
Is the std G4 Mac up to it or do I really need a G4 Dual. I do a fair 
amount of work with midi seq. for brass band and full orchestrations 
for an 83 piece orchestra.
 My brother has a PC which he runs protools and 002 digi rack on and we 
crank out a reasonable amount of audio work. Sometimes live sequencing 
on Logic and adding audio vocals/guitar etc. etc.
  We have used logic from it's infancy on PC's and were never informed 
by Emagic (even though we were registered)that they had sold to Apple 
and basically never having used a MAC except for graphic design work am 
not sure whether we can get away with a G4 for starters as we're being 
fleeced by mac dealers trying to sell us the new macbook pro at close 
to $6000 odd (the G5's here are just as expensive). I have seen a 
couple of G4's & G4 duals up for sale on our local auction site they 
say something like G4 version 3.3 and 4.00. (anywhere from 700Mb to 1.2 
G of RAM I guess we could add more RAM later)
I'm just looking at an entry machine at this stage, nothing over revved!
  I'll upgrade at a later date when I have the hang of a mac properly.

Any thoughts/ideas would be greatfully recieved.

CHUG.