I keep hearing about the benefits of dual channel RAM and wanted to ask a question. I've always been in the habit of never buying RAM from Apple because they overcharge so much. Now, someone told me that for dual channel RAM to work they have to be of the same size (okay, duh), type (figured), *and* brand (why?). Is this correct? If so, should I buy the RAM from Apple? Otherwise, where should I get the RAM to properly match it up? I'm planning to buy an iMac Core Duo during their back to school deal with the free iPod, but I think I'm going to wait until after WWDC, just in case it gets updated. Also, which will perform better- two identical 512 MB sticks, or a single 1 GB stick?