Windows 8 is like putting your iPhone OS on a Mac. It's not for business.
Actually, it is just Win 7, but for people with ADD. It sucks, I end up using keyboard shortcuts for everything in it because the start page is something out of a bad Andy Warhol dream.
I would definitely go with Win 7. It was the first Win. OS that was usable for me. (I use the indexing/search religiously;
much like Apple spotlight.