What’s the difference between:
8GB 1066MHz DDR3 SDRAM - 4x2GB
http://Add $200.00...
(
from 4GB 1066MHz DDR3 SDRAM - 2x2GB)
and
8GB 1066MHz DDR3 SDRAM - 2x4GB
http://Add $600.00
4GB DIMMs are at present significantly more expensive than 2GB DIMMs. It's your choice whether to pay the extra money and have empty slots available for additional future memory expansion (without removing any existing memory).
I presume 2.8GHz Quad-Core Intel i7 is bigger, or more powerful than the 3.33GHz Intel Core 2 Duo of the 21.5” iMac model. Correct?
Generally yes. You can see benchmarks on places like
Barefeats if you want to see comparison numbers.
it appears the CD/DVD problem thing is not evident in the 27” model as it at least was in the 21.5” model. Right?
I can't add anything to what I said on the subject previously.
cracked screens upon opening the box of the new computer, were much more of a problem for the bigger, 27” models that the 21.5” models. Hopefully, Apple has taken care of that by packaging them more carefully.
I haven't seen a report of any cracked screens in several weeks now. But with the gorillas the shipping companies tend to use, there are no guarantees. I once received a pallet-load of computers that the trucking company had driven a forklift blade through. So you never know how your computer might arrive. The prevalence of problems seems to have been alleviated, though.
Regards.