Philip,
I am usually the minority voice on this one, but why not just stick with what is working for you? It works well, you understand the software, and you can easily trade up the "main machine" if you somehow feel the need. Maybe I am not understanding the (admittedly knowledgeable) voices above, but I am really not hearing any clear, significant advantages to an overhaul that sounds pretty pricey and time consuming.
Just my two cents.
