I will receive my new iMac 27" at some point tomorrow and I'm very excited about it. It comes with 8Gb memory, I've never properly used a Mac before I don't know how far that will take me. Some people have said it's more than enough, others have advised me to at least double it up. My main use will be playing games, video editing and web design. It's fairly cheap to buy additional memory through Amazon for example but should I do it immediately or perhaps wait?