I realize this thread is a little old, but the WD20EADS is listed in the following official thread as a supported HD for the 323.
http://forums.dlink.com/index.php?topic=672.0
I find this suspicious since 1.07 is the latest official firmware and claims that support for 1.5TB was added. I just bought a DNS323 assuming I would have to be stuck with the 1.5TB limit, but like mentioned earlier, I see that firmware 1.08 does/should/will support 2TB.
Anyway, I haven't bought any drives yet so I have the same question that was initially asked and thought I'd bump the thread. Anyone have a 2TB RAID1 array with 1.07 firmware? (D-Link, you claim at least one 2TB drive is supported!)