Just an update on my end, i ended up getting the music port, and wow, what a nifty little device. I'm running it on a jetway fanless mini itx board that runs at 1.2Ghz, with 1GB of ram. That's pretty near the nuvo minimum specs for it, and i'm glad to say there's no slowdown at all for me, now. Originally the machine had WHS installed on it, and that was enough to cause a slowdown when accessing other files on the network, such as streaming video, while using the music port.. not so much in the browsing of the music, mind you, just the time it took for it to buffer the song to play. However after going back to trusty old winXP, and stripping it down, removing services it doesn't need, etc. there's zero delay on combing through the library and playing 3 different sources. My library is a decent size too, at 40GB of mp3's and itunes files.
Another thing that helped immensely was using an older version of itunes.. version 8 is so bloated and takes up a huge amount of resources.. although thats solved as noted, by using an earlier version with a lighter footprint, i'm really going to just convert everything over to mp3's sooner or later and ditch itunes altogether.
I'm happy my system right now, as it can keep up with the music port, all while sipping about 6W at idle and 15-20W with all 3 streams going.. so it can be cheaply run 24X7. I'm still considering plugging some change down for one of those new zotac ionitx boards, since they've got a dual core atom 330, and an onboard NVidia 9400M, which can also play back 1080I.. since ideally i'd like to play some video from it every now and then. till then i'll be waiting for pandora streams don't really care if i can thumbs up / down, though that would be great, so long as i can stream some internet radio.