I understand that iTunes is iTunes no matter what computer you use but for overall stability of iTunes and AirPlay, for me personally, I dont think that Apple computers can be beaten!
I'm using an Acer Aspire 5332 laptop currently (W7) and it's 'ok' but that's about it. AirPlay on it isnt anywhere near as stable as it was when I had my iMAC and in comparison, overall the ACER is years behind the MAC computers for me; it's just so slow and bitty whereas my iMAC was smooth and liqued 100% of the time!
Plus the ACER never stops doing updates which seems to slow the laptop down etc...
I think I've learnt to hate MS computers and cannot wait to get my hands on a new MacBook Pro