NAS Box

Can anyone recommend me a NAS box which I can install on site to use as a file server and will let me replicate back to my domain via a WAN so that it is backed up?

I am sick of having servers on sites which have DAT72 drives and no one is managing them but cannot work with their data hosted back at our data center because the connection is crumbs yet at night it will be great for replicating back.

Any suggestions please, only looking at tops of around 20Gb of data.

Look at QNAP NAS boxes. really good they have all sorts bundled in, including replication, not sure if will replicate with something that isnt QNAP though.

Any model in particular, looking at 20-40 users tops. Just need something on site to get rid of these servers and can handle active directory.

QNAP can do AD. The one i have is pretty old, and they have changed the model since, i am not really clued up on the new ones. Have a look on the website there are some charts into getting the right one.

Thanks will have a gander. Just want something to replace these out of warranty servers with something that will cause me little to no hassle :)