Here's what I have. I have the 24" 3.06 Core 2 duo with 4 gigs of ram. I am considering buying the new 27" top end iMac, with the i5 processor, possibly upgrading ti the i7. What sort of speed increase should I be seeing? Is this a worthwhile upgrade? I think I can likely sell my current iMac for around 800-1000. I was doing freelance graphic design and A/V work, but haven't in a while. I was hoping to step back towards that. Thank you in advance.