Hi all. I am wanting to upgrade my 2011, 17" MBP to a 27" iMac - could anyone please tell me how much faster this machine is compared to the one I have? and is the graphics card much better in the newer machine? as I'd like to hopefully play World of Warcraft and Second Life with no lag.. lol. http://www.apple.com/uk/shop/buy-mac/imac Thanks!