Another vote for the Synology DS512J!
Bought empty from Amazon, along with 2 x 3TB WD Red drives, as that seemed the best value by far. A doddle to install and setup.
Mine is plugged into the router directly, but all access for the rest of the PCs in the house is via Wireless, and it is more than adequate as a backup / archive in speed terms, in fact it's great. While I probably wouldn't want to use it as my 'live' drive for everything, I have for example moved all my movies over to there and deleted the local copies.
For my photos, I've set it up so the Synology Cloudstation software syncs my pictures to the NAS in real time; that way I don't even have to worry about running a backup. Then, on the Synology itself, I've installed the Amazon Glacier backup sync engine, and once a day, that syncs the entire photo library and other critical files with Amazon Glacier Storage, which costs a staggering $2.40 a month for just over 200Gb; it's pay as you use, but ridiculously cheap and a very solid off-site backup.
I've been running with the Synology now for 6+months, and it has been rock solid - the software is excellent and very stable. Speed is great and the noise from the unit itself minimal.