Android streaming music from desktop, controlled by another android! I just got a Samsung Galaxy S3, and I can't think of a better use for my old Galaxy S than tucking it away on a shelf with an audio cable hooked up to my a/v receiver, streaming music from my desktop upstairs.  All this works fine, but I have to jump up and down to control what gets played. Now I want the ability to control the music from my new phone, so it's always a pocket away.

I currently use, ugh, I think it's iMediaShare Lite on the old phone, and it streams great using DLNA with either tversity or windows media player on my desktop. Now I just need a way to control it from the other phone. Is there a combination of apps that lets me do this?

I've looked into XBMC and stuff, but it doesn't seem to run well yet on android, and all the XBMC remotes seem to operate like regular TV remotes; they assume you're looking at a screen, so they don't offer song picking abilities directly on the remote app screen.
What you need is a software which acts as an UPnP Control Point on your new phone, and a Media Renderer with Push on the old phone. A control point is capable of exactly what you need: browse Media Server (your desktop) in the same way as you do with your old phone currently, but it doesn't play itself, instead it tells the Renderer "hey, start streaming that URL". Then it just observes the Renderer and can control the playback (if Renderer supports being controlled). That "being controlled" part is called "Media Push": instead of browsing the Server from Renderer directly, the Controller tells the Renderer what to do.

Finding a Control Point for Android should be easy (i won't present any suggestions, just google "Android UPnP Control Point"). There is a solid chance that iMediaShare is a Control Point already. But i am afraid that Renderer with Push for Android is hard to find. It essentialy means that the phone must sit on the network with opened server socket, doing nothing, waiting for commands. And that's perhaps problematic with Android. I already answered one question here on a similar matter and the asker didn't report any conclusion. You are welcome to pioneer the search for such Android app :-)