I could care less about features. I just want it to run AC efficiently and effectively and I don't want it to be obsolete in 2 yrs.
Let me say it another way; do you use Exchange, Sharepoint, etc.? Do you have lots of users that you will need cals for?
Whether you want/need those features drives both your options and math of those options.
For running AC you could use Win7 Pro or Ultimate
