i just went through the process of picking a nas. i use a transporter but same process with squeezebox server. with most nas devices, you will need to leave squeezebox server (sbs) on your computer and change the location the files are accessed to the nas (this is a very simple process which i would be happy to explain if you need some help). there are a few nas boxes that have processors and can run sbs on the nas. this is a different, embedded version, of sbs. there are the netgear readynas duo and vortexbox device, sure theres a few more. there are benefits to both and quirks to both. i ended up going with the simplest path which is a fanless, small nas from seagate called the blackarmor nas 110. very cheap too, $165 at bestbuy. i still run sbs on my laptop and can control with it, the duet remote or an app on my droid. i rip on my laptop with dbpoweramp and the file goes to the nas too. i backup manually with a external usb hardrive (you must do this). i do find that scans are slow (about 15 minutes) but i hope this may improve as they keep evolving sbs (and i get a better laptop).
hope this helps. i found the whole process of learning how to do this overwhelming and confusing. i am not a computer guy but man have i learned a ton about it. happy to share more if you need it...