I need a new computer (I'm still using a 1.67GHz PowerBook G4 believe it or not) and am considering a Mac Pro. Its main task will be photography (Photoshop CS4 and Lightroom 3). I've considered an iMac (and also the recent Mac Mini) but after careful consideration, reading through the Mac Performance Guide and various forum threads I've concluded that the MP's upgrading ability is better suited for professional needs and a better, long term investment. I have some newbie questions: 1) Besides the obvious processor upgrades between models, are there any significant differences I should know about? (I've read that 2008 or earlier MP models use more expensive RAM upgrades, so they're not recommended). Do all Mac Pros have the same expansion slots, drive bays etc? Any sites with a Mac Pro "comparing specs for all models"? 2) When does the amount of cores make any difference? I've heard that for Photoshop (CS4 at least) and Lightroom it doesn't mean much and only mathematical type software needs additional cores. I will probably also use it for video editing in standard (not HD) resolution for now (Final Cut?) and multi-track music recording (Logic Pro?) at some stage, so perhaps this is something to keep in mind still? 3) Do I need to consider a powerful graphic card for my use or will a "basic" stock card do? Mac Performance guide recommends the NVIDIA GeForce GT-120 which apparently comes as standard from Apple. 4) Among the many Mac Pro versions, which one would you recommend I get when trying to cut costs down and getting the most power for my specific needs? The 2011 BTO 21.5" iMac with 2.8GHz i7 was within my budget (I don't care much for the October 2012 update with no user-upgradeable RAM, slower hard drive, no optical drive, no Firewire port and at a higher price than before), so I'm hoping for something around the same cost (or less!). I considered the 21.5" for starters as I'd invest in a pro display later on and continue using the built-in display for the Photoshop tool palette and email, web etc. With a Mac Pro I'd have to buy an external display right away, but I could of course buy a cheap one to start off with. Are there any sites with current prices of the various models so I'd know what to expect? A lot of sellers seem overly optimistic in my opinion, but that could be my ignorance.