FW800=Good, MDD=Bad
Look for a Dual 1.25 or 1.42 which is OSX boot only, (or considered the Firewire 800 machines). In the past 4 months I have had;
1) Dual 867 - NOISY sounded like a freight train.
2) Dual 500 - Less Noisy than 867, but still too loud for a computer in the year 2003.
3) Dual 1.25 - Dual boot, NOISY sounded like a freight train in OS9 - Sounded like an osciliting fan in OSX - no thanks...
4) Dual 1.25 - OSX boot only, FW800, AP extreme.. PERFECT sound, no if ands or buts...this thing is just about silent, even after running for days, during gaming and even folding and gaming at same time...
Hope this helps.
Rob