Hi guys. Im finding my macbook unibody performance slow on some of my Lightroom plugins, so looking for an upgrade. I dont know if I should get the 27 quad-core Imac or the 21. 80-85% of time spent on the system would be Lightroom photo editing, maybe 5% HD video editing, and the rest web surfing and working with Microsoft office. Would the i7 quadcore be overkill? I could afford the quadcore, but dont want to pay for power I wont be using. Im also concerned that 27 would be too big. I'm perfectly happy with the current Dell 22" external monitor that I'm using now.