Well, I bought the 20" iMac C2D and have had it for little over a week now. For some odd reason, whenever it goes into Sleep or Shut Down mode, there's this high-pitched squeal that I can hear while sitting at my desk. Besides that, my iMac is "whisper quiet" (except for when the HD thinks too hard or I have a CD/DVD to work with). I have very acute hearing, so this squeal sounds really loud to me, while not so loud, but still present, to my sibling when he puts his ear about 7 or 8 inches away from the iMac. It's pretty annoying - and I'm sure that it's my iMac that's making this sound since it goes away once I unplug it. I'll be calling Apple Technical Support sometime tomorrow and I really hope that it's something that can be resolved over the phone - I just managed to get it set-up exactly how I want it. I was just curious, but has anyone else experienced this? Was there a way to fix it?