I've got a mid-2009 13" MBP. 2.26 C2D, nvidia 9400M, 8GB RAM and a 750GB 7200 RPM drive (WD blue, I think) The battery needs to be replaced, and it's getting onto 4 years old now (though I think I bought it as a refurb in early 2010, so it's really only 3 years old). I find ML is kind of laggy on it. At least, it needs rebooting with some frequency, and the battery is shot. Also, it seems to run really hot since upgrading to ML from SL (skipped Lion). I could do a fresh install and repair the battery, but I was thinking I could upgrade instead. The newer 13" MBP (non-retina) seem like an easy upgrade. One of my questions is -- will I see a step-down in my video and photography editing performance if I drop from the nvidia 9400m to the on-board Intel HD 4000 graphics. In general, will a new laptop run ML a bit better? Would appreciate any input/thoughts, or experiences in upgrading.