I used to 3 box WOW on 2 computers, but took a break for over a year. At this point I am down to one older computer.

I was looking to either build a new computer with the 2500k sandy bridge processor and use it to 3 box by itself, or I would use my old computer to run the 2 slave accounts while I run the main account on the new computer.

My old computer is getting tired and I would probably either upgrade it or just build a budget 2nd computer if using 2 computers was "better".

What are the pros and cons of 3 boxing WoW on 1 computer vs 2 computers?