Linux will probably run fine on those specs, remember Windows has a ton of overhead in terms of RAM and storage.
I'm not going to buy the high-end version if it requires me to buy the prepackaged Windows license however.
How much memory does Mac OS X Yosemite need?
How much engineering effort is spent on optimization and improving performance, as opposed to changing the look'n'feel and adding consumer-focused features?
Edit: oops. That paper isn't evaluating performance, as I thought it would.
Of course you can run something else, but for a hassle free experience , ubuntu seems like the best choice.