Stream content from iTunes to AppleTV and Airport Express

Question

I have an Apple TV in family room which is wirelessly connected to my home network. I also have a PC connected via Ethernet to my network. All my music is stored on an external drive connected to my PC (I don’t store any media on the ATV, as my music is well over 400GB). This setup works great, and allows me to stream content from the external drive to my ATV which is connected to a stereo.
Next, I purchased an Airport Express, connected it to a second stereo in my basement. After spending 3 hours trying to get it connected to my network, (I had to disable all wireless encryption, and use MAC filtering to keep network secure), I am now able to stream media from iTunes on the PC, to the stereo connected to the Airport Express.
What I would like to do now, is be able to select a song from the Apple TV (using ATV remote, or iPhone Remote), and have it play in both places. Since the media itself is coming from iTunes running on the PC with the external drive, and it gets streamed from there to Apple TV, how can I also stream the same content to the Airport Express?
The folks at the Apple store say this is a feature, but no one seems to know how to make it work. I have also read hundreds of posts online, and some say you can do this, others say you cannot. All of those who say it is not possible, state you cannot stream from ATV to AE, but in my case, the media is not on the ATV, it is on the PC, and I just want to use ATV to select the song. From there, it would be iTunes that would send the content to both the ATV and the AE.
Can someone help myself and many others put this question to rest - can it be done, or not?

Answer 1

Thanks for the reply. Just as you indicated, I figured out how to use iPhone remote to tell iTunes on PC to output to Express, Apple TV and PC, and that works great - I can even turn on/off any of the speakers from the iPhone - this is so COOL!
While you answered the question, I am curious about the architecture of all this...If the media is actually on the PC and is controlled by iTunes, isn't the Apple TV doing the same thing as the iPhone Remote - just telling iTunes what to play, and iTunes sends the content to whatever speakers are defined? Keeping that thought, if you can control iTunes via iPhone Remote, and the content will play on any speakers you select, then it would make sense that you could do the same thing with the Apple TV menu - tell iTunes what to play, and let iTunes send to whatever speakers you have selected.