Re: mac pro vs. imac
No worries Aussie about the report. As a disclaimer, I'm a Final Cut Pro and Motion editor/instructor so I don't want you to think I'm an audio expert. However, I also have experience using Soundtrack.
That being said, I know that using a modern Core2Duo Intel iMac with the 2.8Ghz Extreme processor will run Logic 8 with little or no problem. I only recommend the 4GB of RAM if you are a serious user who wants nothing to stand in his or her way. My Mac Pro is stacked with 8GB of RAM because even though Final Cut Pro will normally only use about 3GB of it, I need to be able to open Motion, Photoshop and Soundtrack Pro simultaneously and that's when the extra memory comes in handy.
My point is that if you have 2GB installed and are working on a large multi tracked piece, you will probably be maxing out your RAM between OSX and Logic. So spend a few bucks on, at least, 1GB more of RAM to give yourself some overhead. Good luck.
FYI, I just set up the new 24" iMac for a client recently and I'm very, very impressed with the machine. It's display is 2nd to none and on basic apps like iMovie and Garage Band I cannot tell the difference in performance between it and my Mac Pro. Very highly recommended. Enjoy!