Here's what I do. I use 2 computers for my shamans, 3 if I run my other group(3rd one for the healer alone). One toon on the 1st computer, the other 4 with maximizer/keyclone. If I pvp, I put 2-3 on the 1st computer, so when my main dies, I switch windows with no problem. You really don't need a big spec computer to run 4 windows. You won't go over 40fps anyway in a given window with keyclone.

If they ban keyclone, guess I could setup 5 computers. But I already have around 10 in my house, and 5 are in my room alone(2 for my wife, 3 for me). The kids have the rest. Don't need any more heat or wires in my room! Our bedroom is pretty big(30x30 feet), and the computers alone can warm up the room this time of year.