It's just very frustrating as the Apple Store is not local, and the 27" iMac isn't the easiest thing to carry around.
The pixel anomalies weren't there before I took it in to have the ODD replaced. I expected that Apple, of all companies, would have done the best job possible. I hope it is just dust, and not newly dead pixels.
I'm sure Apple will do the right thing, but it's just such a pain to have to take it back to them again (it will be my third journey there in a week).
Thanks for the responses.