Just got a new DP 1.25 today. Since my previous Mac is an iMac, I don't have direct experience with the orig MDD's, but...
I would say the my new one is audible (certainly louder than the iMac when the fan is on), but there is no "whine". It's about the same the same as an average Intel PC. The Apple store had both old & new style MDD's on display, and when I held my head up to the top front of the case, there was a definite difference between the two types. The old ones had a noticable whine which the new ones didn't.
The one I brought home was DOA (wouldn't boot beyond the gray apple screen!!! - another story) and the second one they gave me sounds the same as the first, if that's any help.
I got the new 20" display with it and it is fantastic! A great display for a great price. If anyone cares, mine has a Seagate Barracuda V hard drive.
Even though there is only a combo-drive installed, iDVD3 is on the hard drive. Guess it's time to order a Pioneer A05 to slip in, since xlr8yourmac has numerous stories of success with OEM internal Pioneer drives with iDVD3.
Keith