Can't answer your question, but I'll ask one in return...why do you NEED to upgrade? Unless there is a specific problem that upgrading is the only cure for, seems like a moot point.

We're still using a P4 1.6gHz machine that has had only one issue in the 18 months of daily service...Tracks 18 at a time without so much as a hiccup...thought about upgrading a time or two, but I can't honestly answer the question of 'why?'

The answer is very simple: I expect a bonus from the company I work for :) The next opportunity will arise one year from now (if ever). I guess I can still sell the stuff I have now to cover the upgrade costs (in part at least).

Well, upgrading is always a nice thing to do and depending on what you have now you may just be able to upgrade the CPU to get a little more oomph out of it.
Currently I have not been reading anything on newer stuff as I am waiting on the new Intel stuff to be released. Which should be sometime this year! Suposedly Q2 or Q3. 800 Mhz FSB systems with some serious data throughput!
I currently am running the P4PE and have to say it's rock solid!
Opus