Thought I'd mention this as quite a few people ask what sort of NAS they should get, I picked up one of these from my local PC World last week, £199 for the 1Tb single disk version, on paper it appears to be similar to the Netgear ReadyNAS Duo, but cheaper.
There's not a lot really for me to say about it, I plugged it into my router, went through the setup CD and copied my music directory onto it (that did take a while, even with the new gigabit ethernet card I put in the PC, I have a gigabit switch that they were both connected to, 88Gb took something like 6 hours, I wasn't paying that much attention unfortunately so I can't be any clearer than that).
Pointed the Sonos at the new share, gave it the username and password I'd set up, indexed the share, removed the one pointing at the PC and everything worked fine, Sonos happily plays just as it did previously.
The Stora seems to be aimed more at the less-techie sort of user, the interface is quite simplistic and doesn't give you a huge amount of control at any kind of low-level but to be honest, even though I'm a UNIX user, I didn't really care, I only wanted it so I could play music without the PC on, which it's doing, I'll be surprised if I delve much deeper than that. It's now sitting on my rack, next to the router and Sonos ZP90, I can't hear it making any noise, either fan or disk and, from what I've read, it uses about 11 Watts, maximum, which is less than an "energy-saving" lightbulb, so I've got no qualms about leaving it switched on permanently.
The main gripe most people will have is that the "advanced" options are only available if you pay $19.99 a year for a Premium subscription, I had a look but there's nothing there that I'm interested in (I don't tend to upload photos from the web or need access to it from elsewhere. Also you MUST have internet access to perform the setup, which is stupid, but other than that it should suit most people.
One proviso, the guff claims that it supports iTunes, however I'm NOT an iTunes user, so I can't make any comment about how well it works with iTunes (or not).