Ok folks. I work at a small company that handles audio and video discovery for criminal cases. About once every two weeks, I get 250-300 GB of uncompressed AVIs that need to be transcoded into the major formats (wmv, ogv, m4v, to be precise). I am currently doing this on my Core 2 Duo unibody Macbook (early 2008). I use ffmpeg along with a few home-brewed scripts to handle the load. I do not use FCP, or Quicktime for this task. With my current setup, this process will last 4-6 days, depending upon the complexity of the video and the quantity of material. I'd like to get a dedicated machine and my budget has limited me to either the highest-end iMac (quad core i7) or the lowest end Mac Pro (quad core Nehalem, at about $300 more). Here's my question: is the i7 good enough? Will there be a noticeable difference between my current setup and either of the potential machines? The substantive difference, a monitor, is not necessary for my current setup but it might help a little.