I have bought a DNS-323 a couple of months ago and it is perfect. Really simple if you just want to plug and play and share files. As cheap/expensive as you want because you supply the drives - the WD Green drives work very well in them.
If you want to get fancy, you can use the custom firmware available for it (just google DNS-323 and you will see the extensive modding community).
Has iTunes, uTorrent, media server capabilities as well, can't speak to them, I just use it for file sharing and back up.
Perhaps I'm being a little daft (more than likely, I seem to have a real skill at it), but what is the configuration procedule for these NAS devices? IS it something along the lines of:
Plug in Device Device
Connect to router via ethernet cable
Fire up a PC / Laptop
Navigate to configuration IP (I imagine something like 192.168.2.100)
Configure the IP to the range requested and set as static (192.168.1.35)
Access the drive via 'run' in windows by typeing '\\192.168.1.35\'