I also sent mine in for the loud, buzzing disc drive. I actually just did the advanced replacement and had a new Wii in 2 days after calling it in and then just sent my old one in.
Though, I believe the "new" Wii is actually a refurbished Wii, as are all of them coming from the repair facilities, from what I understand.
That was at the end of July. Now my second Wii is starting to get loud again and clicks A LOT (way more than it did before); it also seems to take longer to get the discs up and running. I'll just wait it out and see if it gets worse.
Nintendo needs to get their act together. I've owned almost every console from Atari 2600 until the Wii (and sometimes multiples of some of them), and the Wii is the ONLY one to fail on me.