I've been lurking on this thread as I've been trying to figure out how to make WMP11 perform well with the RX-V2700. I did a fresh install of XP SP2 on a box intended to do nothing other than serve music to the RX-V2700, applied all the MS patches to make it current, installed WMP11 and copied a music library of about 450 CDs to the XP box. I had the same experience as others - slow response, play- artist- and song- lists that sometimes were there, sometimes weren't. And especially frustrating was that a playlist could be empty or show only one song one second, but back out of it and then click back into it and it would have a different result. That result could also be achieved while actively streaming and listening to a song from the WMP11 server over a hard-wired connection, so it doesn't appear to be a connectivity issue.
After reading the posts above, I moved the library to Vista. WMP11 and/or Vista seem to be picky about where the library needs to live (e.g. I could see the playlists and albums when located on my local USB P: drive but would get a connect error from the RX-V2700 whenever I tried to play a song). I moved the library to C:\Users\Public\Music and then it worked as expected.
And as reported above, the PC/MCX GUI on the RX-V2700 works quite well when pointing to the Vista box. If I hold down the up or down arrows, the GUI will effectively scroll a page at a time. It's quick, responsive and predictable in result. It's the one surprising thing I've found Vista actually did better than XP.
I don't know what difference in implementation is between WMP11 on XP and Vista, but the results are markedly different for two boxes sitting side by side and hung off the same router. So for now, the library sits on Vista and all is good.
I still have an e-mail into Yamaha on the issue, and would love to see a firmware update that gave the option to pick the first letter of the song or album or artist to jump to -- effectively enter a list at somewhere other than the top or bottom, or the ability to do a page up or page down, but for now the curiosity continues as to why Vista seems to play much more nicely with the RX-V2700 than XP does.
And a couple quick thoughts about why anyone would want to stream music. For us, it was convenience. We unlocked access to all that music that was held hostage in racks of CD jewel cases. Grab a case, switch a disc, open a case and find out the disc was in the car, on the boat, blah blah blah. Now if we want a song, an album, and artist, it's all there under our thumb. We're no longer manipulating physical media, instead we're just enjoying the content. And the CD player has actually been taken out of the cabinet. When we get a new disc, we feed it to the PC, rip, listen, done. It's not for everyone, but it was a big part of why we chose the RX-V2700.