Windows 7 .. Worked with Windows 98 , 2000 , XP , Vista , Windows 7 .. And am more comfortable with Windows 7 and i <3 it .. ;-)
At present i am using window 7. before it i was use only window xp both are the best operating system.
Microsoft or program experts may provide Windows 8 Tools along with upgraded software which will support to Window 8. This latest operating system having upgraded features and applications which are making your use better and more faster.
I am also using the same as you are using i.e Windows 7 and now i am witting for windows 8 in few days i am going to install.
I am using Windows 7 Premium. I am a little sleptical about Windows 8 so might hold off a little before upgrading.