Win 8 is going to be a non starter with its inability to boot to the desktop, where a front end would reside.
I was one of those that tried to push Win7 as an alternative when it came out, and to this day there are still RR plugins (if you choose RR) that do not play nice,
When you can find someone to write a complete metro app (oops, Win 8 style app) that gets the job done then you can talk about Win 8, until then, build your own with the new mini-itx motherboards that support 6G Sata and USB3 and get a good SSD (6G Sata of course, also called Sata 3, WTF?) and intall Win XP on it for the greatest functionality, Win 7 will buy you speed in exchange for no speech recognition and making sure you have the EXACT drivers that function.
Better yet, don't bother. You will thank me after having some time in your life!