another option is the apple airport extreme. Now the way I use it is sacrilege to alot of folks here, but I am working on digitizing my entire music collection (live, CD, vinyl), into 256Kb AAC, and use Itunes to serve it. I have 2 of the airport extremes at the playback in my bonus room and one serving my den/outside speakers. the Iphone (or itouch which I have) has a free remote app, which allows me to control itunes from it and I can tell itunes which speakers to play to. Pretty fantastic to have your entire music collection available at any moment.
The reasons I went with the lossy format vs .wav is a couple of things. First, the amount of space it would have taken to use wav/flac for everything I have would have been obscene. My lossy Itunes library is almost 650Gb. I can only imagine how out of control it would be at wav/flac. Second, I like having the options...I mean if I want to critically listen..I still have CDs/Vinyl (which I still listen to a ton) and the main playback system. But this gives me flexibility. Third, I also do quite a bit of listening outside of the house on my itouch...and again access to my entire library for that is desirable.
Brians suggestion is a great one as well, as I had a squeezebox for a while. I just ended up moving to the airport express for a different set of requirements.