I have a 13" 2.26GHz C2D MBP with 8GB RAM and a 750GB 5400 RPM WD HDD. Ever since I moved from Snow Leopard to Mountain Lion, the fans are a pretty constant run. In general, it runs pretty hot. I do use it a lot in clamshell mode, which I'm sure has something to do with it. Just curious, as the laptop approaches 4 years old, I was thinking of upgrading for better performance on some apps like Lightroom. Would a new i5 or i7 13" MBP running a single spinning platter HDD for some reason run cooler than my current MBP? I'm thinking here maybe the CPU wouldn't have to peg to 100% as much as it does now? Alternatively, what if I swapped out the optical bay on my current MBP for an SSD to host the OS and apps. Would that a) improve performance, and b) help it to cool off a bit, since it wouldn't (perhaps) need to access the spinning platter as much?