I have two Win 7 PCs running iTunes 10.7.0.21 one is a 64 bit maching and the other is a 32 bit. I can see the Air Play on both and can see the AE speakers, however, for some reason I can not select any speakers except the PC speakers on the 32 bit PC.
This problem only started after I updated iTunes to version 10.7.0.21. Never had a problem with the AE speakers until now. Funny no problem on my 64 bit PC only the 32 bit one.
AirPort Express 802.11n (1st Gen), Windows 7