Hi. Well, I will like to do everything with my iMac. Gaming too. So, I'm thinking about going for the 27" model. I can buy the 27" i5 and 4850 refurb. or the 27" Core 2 Duo new for quite the same price. I also can buy the advanced 21'5 for a bit less. Which should I do? What are the - of a refurbished model?