I have a 750GB Caviar in my MP and I can attest to it's muted tones (compared to the 160GB barracuda that it shares the case with).
That is, until 3.5" solid state drives become mainstream.
Super Talent makes a 3.5" 256GB SATA SSD, but if the 2.5"/32GB sells for $770 on newegg, I can only guess what the 3.5" version (at 8 times the capacity) sells for.