The yellow tint issue has been [http://www.macworld.com/article/146754/2010/02/yellow_iMac.html|recognized by Apple], and you should contact AppleCare and they will make sure it is replaced. Currently no one is exactly sure why this is happening, but I'm sure then when it's figured out there will be a sanctioned repair method, and iFixit will have a guide (or someone will make one).