Yes, I know russian, but we are not in the Russian forum, so maybe it's better to communicate in Enlgish here
. About the keyboard - I didn't say about the PC keyboard, I know that it's just for fun when you play with the PC keybord (I tried some programs, for example FruttyLoops, and totally understand that playing with pc keyboard cannot teach the real piano playing, but it's fun) - so I said about midi keybord that can be connected to the PC (but maybe it can be difficult to implement input interface with it...)
I played Perfect Piano app on android with my mobile phone - it's too small but fun and I can play some small songs.
Then I bought Google Nexus 7 - and Perfect Piano is much better with it, becouse I already can press kyes almost without any issues. So I can connect it to the audio system and play some music.
Also I saw an ad. recently - new computers or monitors were presented (I don't remember for sure). They are big and have multitouch screen - so we can play as with the real piano.
I undestand that the real piano is the best instrument to play, but for most people such virtual keyboard (or midi keyborad sometime) is the only one way to play the music.
Good Luck with your project!