PianoCheetah is a windows app.

If you can get windows8pro to work with it, great. But no touchscreen specific stuff.

Sound source will be whatever midi devices you have hooked to your pc. Or else the built in .WAV playing softsynth that pianocheetah has.

I plan on moving PianoCheetah to Android tablets in about a year. But that'll take a while to convert all the c++ and win32 API into java and android API.

I don't plan on porting to mac/ios as it seems to be in a downward spiral to me.

Android still needs audio latency fixes and a decent midi api (not to mention hardware midi<=>usb interfaces). But I think I see those off in the future. I'm pretty sure I'll be rewriting all my dang code in about a year's time to get onto Android and drop Windows. In the mean time, windows doesn't suck too bad.