I've had Napster for the last few months and I love the selection. The files are 128 kps WMA's, and the sound quality is good. A little crisp on the high end, maybe, but plenty good for the price.
However, I've had problems with the DRM software. I run win2k as a "power user" priviledge level, but Napster itself won't run unless you're logged in as "Admin" (this according to Napster tech). So I have to log out to download songs, and it appears I have to be in admin mode for MC to import the songs. Once they're imported I can play them and do all other library functions, including renaming, at a reduced priviledge level.
Playing a DRM song is a two-step process. You hit play, and the program must first verify the license. First song of the day, it can take a few seconds. After that, things go smoothly unless you are doing heavy multitasking. Then the DRM step can cause significant pauses. This is a DRM thing, not a Napster or MC thing.
If you're running your music off a dedicated server, multitasking shouldn't be an issue. The restrictions are the DRM are fairly liberal, surprisingly so. There should be a way for you to do what you want over a network, although you may need to work it a bit.