Just my 2 cents here - I started boxing wow about 2 months ago. Most if not all of my info gathering I attained here on these forums. There is a wealth of knowledge here for the casual Multi-boxer like myself.
When I first started I was amazed at some of the various PC setups that gamers were using. Breath taking configurations.
The only question I had was if I would really enjoy playing this way. That question COULD have cost me thousands of dollars. (And a verbal beating from my wife)
I decided to go the most efficient way for ME. Since I had 1 top of the line PC and 1 not so top of the line that was readly avaible, I'd go the software route. Im glad I did.
I had the boxing up and ready the same day that i created the accounts. Im not using anything ground breaking either. Keyclone and mutliplicity are the only programs I use other then in-game macros. My main pc runs 3 accounts while the secondary pc runs 2. I BELIVE everything runs flawlessly. My server is PVP and I PVP often. I only have 2 monitors up( Main is a 23" widescreen running at 1900 * 1200 btw thats what i use on my main toon with all options maxed including sound)
One last issue im content with is the electrical use and heat generation of the set-up. I only have to look at 2 monitors and not become over burdened by stage show lights.
Good luck and welcome aboard.