Well I run W8.1 on my laptop. That laptop is basically my portable development environment with VS 2013. It runs just great! I have also a main PC which is my primary development machine with Windows 7. Both are just great, BUT the multiple monitor thingy in Windows 8.1 is just much better. But still I never would buy W8.1 for my main pc as long I have the OEM Windows 7 for it. Talking about differences in programming, I don't notice any problems with WPF, Windows forms, ASP.net or other technologies from .net or Java. I guess it depends on the power your Windows 8.1 machine has. As well I have to say (even with a less powerful CPU and GPU) my Laptop (windows 8.1) boots 3-4 times faster than my Windows 7 device.