Don't try to make me happy, you're the one that has to use it. I just say don't dismiss Win8.1 out of hand. If you try it and don't like it (for legitimate reasons of course), then don't use it.
A couple questions. What is MS Accounting? I googled it and got a bunch of unrelated hits. Also, why use MS SQL 2005? It's fairly old. Could MS Accounting use the lightweight Windows DB app (previously called SQL Express...can't remember the current name)? SQL server is a pisser to maintain anyway even before you take into account how easy it is to misconfigure it and make it a vector for exploits.
Again though, you're the one that has to use the device on a day-to-day basis. Use what makes you most productive and happy. Right now here at work, I have an OS X box, a Ubuntu box, and a Windows 2012 R2 box sitting in front of me.