Hardware Boxing, 3 Comps, 5 Accounts. Anyone tried this?

I was thinking of building 2 alt comps to run a double instance of keyclone on dual monitors and to link up to my main PC running a single, larger monitor. I won't need a webbrowsing machine/monitor because I already have a laptop that is perfectly capable(actually more than capable, its an XPS 1530). Yesterday when browsing around at possibilities of running a % box set up, i see the power consumption can be quite a nightmare. So I have previously picked out parts for 4 alt boxed costing just under $500 each on newegg but then I thought, what about running 2 dual SLi Dual Core comps with just the basics and using Keyclone in combination with hardware and Synerygy and a Main Computer to run 5 Instances of WoW. Has anyone tried this or can help me speculate on the possibilities of making it happen?

I run 3 computers with 5 accounts. Center computer runs my main toon and each side computer runs 2 WoW alts.
I use Multiplicity and Keyclone everything seems to be working great.

What kind of hardware do you use to hook your boxes together? KVM Switches or anything like this? Do you use Xkeys?