I just bought a card for 1500 HD PCI interface and € 96 for € 800 then a G5 single processor for 200 €.
I do not regret at all .... Of course the G5 train for other applications, but protools is perfect because the card handles all ....
In short, Digidesign is very hard for us to spend money while there are still large studio with a G4 running!
Previously had a G5 Quad and a Digi 003 .... it works just as well, but with better quality.
Of course I could not do the update and I should stay in ProTools 8 ...
not care, protools is at the end of the chain of recording and making the sound is good before!
So keep your € microphone, cables, preamp, compressor .....