Hi! Here is how I got my 2 terabyte drive to work with XFS:
The USB HD model is WD Elements Desktop 2TB if i remember it right.
I had it NTFS formatted from FAT32 - router recognized it, but the formatting did not work.
I deleted the partition in XP disk manager - the router did not recognize it at all
...But when I used Norton Partition Magic 8 and deleted partition from disk,
added new extended partition as unformatted - voila!
HD was recognized and got formatted as XFS succesfully.
My FW is WZR-HP-G300NH Ver.1.74
(as I tried to update it first from 1.73 to fix the problem)
Status is now 1% filled on the 2TB drive, as it is painfully slow to transfer files in,
and I will see if it works fine over 500GB...512GB also,
as I have 3 more of these large drives to go... =D