Hi all. I'm in sort of a peculiar situation. I have owned (not at the same time) both the launch day 27'' imac and the most recent one released earlier this year. There are noticeable differences if you have had both, so thought I would go over those here. a. The Screen When I had my launch iMac, I like everyone else in the world, had the yellow screen issue. I went through 3 replacements until I got one that was not as bad as the others. But the problem persisted and I eventually couldn't take it anymore and sold the iMac. b. Disk Drive On my third replacement of the launch iMac, the SuperDrive slot must have been cut poorly because EVERY SINGLE CD I put into it would get horrendously scratched. I've noticed the new iMac I have now has a plastic ring around the inside of the SuperDrive slot, completely negating any problems that may arise because of a poorly cut slot. c. Hard Drive The hard drive in the launch iMac was a seagate brand drive and every time the system was doing nothing, the drive would park its heads, which makes sense. However, all the drives I got would make an INCREDIBLY loud clicking noise when they parked. You could hear the drive spinning at basically full speed and then CLICKKKKKK- and it instantly stopped. I knew from owning previous seagate hard rives that that behavior would kill the drive in a matter of months, so I was not happy at all. Likewise, the new iMac has a Western Digital drive, either a caviar blue or black (you can usually tell by looking at the serial number in system info, but apple used drives with custom connectors so the serial number system is slightly different, so I don't really know for sure.) Anyway, the new drive is silent, except when accessing data. I couldn't be happier. In conclusion, the things I've noticed are very typical of any apple product. A brand new design is introduced and there are usually many problems with it until the second or even third revision. The older launch iMac had many issues, while the new one is flawless. Sorry if that was a huge wall of text, but I just felt like letting people know what I've personally seen.