I am about to buy a new 13" MBP. Leaning toward the low end. I use it heavily for all Office applications, plus Photoshop, iMovie, iPhoto etc. No gaming. I'll install VM to run Win 7 on occasion. Where do I get the most bang for the buck to improve performance: upgrade RAM; SSD; or i7? If SSD is the best bet, what brand etc? Thanks for the advice.