Okay so I got my 21.5 i7... played with it for 2 days and then installed another 8GB of Crucial memory which I purchased from Amazon. Several strange things started happening. When I was swiping through screens I would often get a purely gray screen. In addition when that happened, I couldn't see the other screens (windows or whatever it's called) at the top of the screen. Finally when I installed a game for my daughter it (from the MacAPP store), it would freeze the entire computer. I uninstalled the game and only got the grey screens. I've uninstalled extra memory and everything seems to be MUCH better. So I'm back at the original 4GB from Apple. Ironically the computer is actually running faster. So I'm assuming I had a bad batch of memory. Any suggestions? Anyone have this problem before? I'm wondering if I should just stick with the 4GB or pay Apple the ridiculous extra $$$ for their memory or order another batch of 8GB directly from Crucial.com??? A little help would be greatly appreciated.