I would go Windows if you have the license..
A) you have paid for it..
B) its very easy (and just as fast, maybe faster because of the OC tools out there)
C) dummy plugs are not a limiting concern because they are ridiculously easy to make -> http://www.overclock.net/folding-home-guides-tutorials/384733-30-second-dummy-plug.html
fyi: I like to wrap my dummy plugs in electrial tape once I have finished the 1 minute construction process.
Also the new GUIMiner with Phoenix and phatk support is awesome!
I have 3 rigs all setup the same... I get them running with a monitor hooked up (and 1 dummy plug in each of the rest of my videocards), then I go download tightVNC http://www.tightvnc.com/
.... Once I know tightVNC is installed and I can connect to the machine, I shut it down. move it to its new "home" in my house, give it a network connection, power, and a dummy plug for that last card and turn it on.. Then I walk back to my laptop, login over tightVNC and kick off my miners (and usually Afterburner because I like to keep track of my temps and tune voltage & clock speed).
* You may have to go into to your screen properties and actually activate the other monitors to get all of your GPUs to activate
Don't use Remote Desktop.. MS is smart enought to know that a remote desktop connection isn't actually using the screen so the GPUs are disabled/blocked from your session. Thats why I use tightVNC.
(here is the ubiquitous "donate" wallet ID 13d46unynPiuspsND1fC3kuPeb8szgWv4T)
Thanks! This post answered a couple questions I had.