This is an additonal post to the earlier one that I did on "setting up your HDD's for editing." I'm linking to my post in the Adobe Premiere Elements>Tips & Tricks sub-forum. This article furnishes two links: one to that I/O Sub-system article and to a companinon article. It is both a preamble to that article, and a continuation of it. Link:
http://forums.adobe.com/thread/433940
Harm Millard is the author of both linked articles. He has been a respeced and significant poster in the Adobe fora. He has a very strong IT background, and is an accomplished video producer and editor. This is his equipment compilation on the ultimate editing machine. It's based on what he's actually built and tested, or on units built by others but benchmarked in real world editing environments - not just some number-crunching standard computer tests.
While one will probably have to make some compromises, and might not need the ultimate system, as Harm describes, the information and knowledge gained will pay off. Yes, Harm's suggested machine would be the paradigm for today, and we mere mortals would have to settle for less. Still, the knowledge imparted will be useful in making the ultimate buying decisions.
Good luck,
Hunt