Hoping someone will be able to help me; is the DVD actually required for installation or do you just need to upgrade your battle.net account as I started installing and it was reverting back to an earlier patch so I cancelled the installation.
A blue post JUST said it will revert your client to 4.0.0 but it will update it again DURING the installation
"If you install from the Cataclysm DVD, your game will be temporarily reverted to patch 4.0.0; however, since those patches are already downloaded on your computer, they'll just need to be reapplied. This will happen automatically during the installation process, with no additional work on your end.
All in all, you shouldn't notice the difference -- unless you've deleted the previous patch data, in which case, you will need to re-download it. If you're fully patched, though, the installation process from the box DVD should take approximately 10 minutes.
(The alternative, just for perspective, is to sit through an 800MB download. This download will occur if you upgrade your account, but do not install from the Cataclysm DVD or opt into the digital pre-purcase/pre-sale download. If you've deleted patch data prior to patch 4.0.3a, then that may be the best option for you.)"