I see the 17 inch one does not have a video upgrade on the apple web site does that mean the 20 inch only supports 256mb video.also I see that it's like $360 canadian to get 2gb ram upgrade from apple.can you buy cheaper third party ram to save money and put it in your self if so how hard is it to do.also does any one know if the cpu in the intel imac is upgradeable. Thanks