Also, in general, in the past anyway, have twice the amount of RAM you think you need, and twice the hard drive space you think you need, or at least keep some free space on your main hard drive for a buffer (like a third of the drive empty) -- for Photoshop in particular, but also for video editing (if that's on the agenda). Our Mac is 5 years old and still holding strong, but it needs more RAM and I'm thinking of putting an SSD in to boost the system speed.