Only the G5 iMac, and not all rev.s had that feature. None of the intel iMacs have a removable rear panel. There are other subtle diff's. I think some of the G5 rev.s could be VESA wall mounted, but now only the 24" is VESA compatible. There are quite a few people who have upgraded their own HDDs in the intel iMacs, be removing screws and pulling the front of the case off, and then carefully taking the screen out to get the guts behind it. If this is something you want to do to upgrade your HDD, I'll try to find you the threads and links to the process. I don't think it's all that hard. But I can't see any reason you would change out your optical drive, and at this point I don't think there are any graphics cards available through any retail channels that are compatible with the special MXM?? adapter/interface that the video card plugs into. But I know of at least two people who swapped out HDDs to 750GB on their 24" and 20" intel iMacs.
