I have an early 2008 15" MBP with 4 GB of RAM, and I just installed Mountain Lion. Over the past year, my MBP has finally started feeling slow to me. Aside from the usual web surfing, Mail, and MS Office apps, my primary uses are Aperture, Photoshop Elements, and Logic, all at a hobbyist level. The logic board went out earlier this year, two weeks before my AppleCare expired, so I was able to get that replaced for $320. (Since my computer wouldn't boot, they couldn't check whether the infamous NVIDIA graphics card was the culprit.) My next Mac probably will be a rMBP, but I want to wait for rev B, and also for the 512 GB SSDs to come down in price some more. I found some threads from 2010/2011 in which people had replaced their HDDs with SSDs in similar machines, in the hope of getting another year or two of use from their aging Macs before upgrading, and were pleasantly surprised by the speed boost. Now that said year or two has passed, is there anyone who has done this who now plans to get yet another year or two out of your Mac? Would you recommend upgrading such a machine now? I'm considering replacing my 7200 rpm 320 GB HDD with a 128 GB SSD (which are now pretty cheap) for the OS and programs, putting the HHD in an optical-drive replacement caddy for data files, and moving the optical drive to an external enclosure, which would cost between $150-170. I'm weighing that against the facts that the components are over four years old and aren't getting any younger (although I've gotten seven years out of Macs before), the processor won't get any faster, and there's no guarantee that the infamous NVIDIA card won't go out again. I don't want to drop two grand on a new computer just for the sake of it, but neither do I want to put more money into an old computer if it would provide only a modest overall speed boost in which case, I'd live with what I have until I can't stand it anymore.