Well I just got both of my 400 GB RE2 drives today. I ran them for a while to hear the noise and feel how much heat they generate. My initial reaction after running them for 4 hours is that they are extremely quiet and you don't hear that windup high pitched noise anymore. They must use a gentler startup speed and ramp up slowly. I can't hear any head noise such as clicking. Heat generation is on par with my old 100GB Caviar drives. I would say around 120F.
Western Digital 400GB RE2 drives and my eMachines M6805
Your looking at $350 in drives from ZipZoomFly.
Installed and running in top two trays. The good news is the only thing I hear is the CPU and video card fans spinning! The bottom tray is my old 30GB drive from 2001. lol. It is a sole survivor of the days when comparable sized IBM drives were known as "DeathStars" and had the click of death issue. It suffices as a usefull storage device between my three desktops. Someone remind me to pick up an external USB or firewire case and get into 2006 trends. The reason I stick with this is because transfers are faster. Oh well...to each his own.
The reviews say that Windows XP load time is significantly faster with the RE2's in RAID 0 than with the Caviar SE drives in RAID 0. Thanks in part to the four-100GB platters. The total combined space with these drives will be around 760GB. RAID 0 performance testing should be impressive. Let's find out. More to come.