Per your link here is the first article found that came up on google (
http://www.dailytech.com/article.aspx?newsid=8374):
A few weeks ago, a Digitimes report suggested that AMD had accidentally released a large quantity of broken HD 2400 and HD 2600 cards into the market. This created mass hysteria in the hardware world, and even sparked a mass recall from one manufacturer. However, after the dust settled, AMD and their partners did some investigating. What they found shows that the entire situation was overblown. ASUS representatives say that ASUS has not received a single broken HD 2400/ HD 2600 card. Gigabyte and MSI also have not received broken cards. Most engineers suspect that the idea of a defect/recall came from Acer, who ordered a large quantity of HD 2400 and HD 2600 graphics cards with UVD (Universal Video Decoder) disabled. When news of the UVD "problem" reached the market, the hardware world went hysterical, while Gigabyte, MSI, and ASUS all did internal testing to confirm no problems with the HD 2400 or HD 2600 series.
AMD engineers have a statement to cover the entire HD 2400/HD 2600 fiasco: "Any report claiming that defective HD 2600 and 2400 [cards] are recalled in the channel is completely untrue".
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My machine is working flawlessly, it's never hung, I don't have dead pixels and my graphics card works fine in 3d games. I'm 99% happy with my choice. The missing 1% is due to the lack of friends I'm making cause I'm geeking out with my new machine.
I do know some people have had issues and I'm truely sorry they are experiencing them. I think the overall % of defective iMacs is probably pretty darn small. This would be true for any consumer product produced. You can't manufacture something over and over without some degree of error.
That being said, you are being smart to research before you buy. Put yourself in someone elses shoes... does an article title like yours help them out? I know what my answer would be
Cheers!