My girlfriend recently decided to replace her 4yo PC laptop with an iMac, mainly for video editing. Her budget is only around $1500 though, which limits her to the 21.5" iMac's. Would the low-end 2.7GHz model with 16GB ram be suitable for video editing? Or would the 2.9GHz with 8GB ram be just as good/better? I'm trying to convince her to spend a little more and get a 27" so she can install the extra memory herself, but she's afraid that it'll be way too big for her.