A:Answer from the WD website - I would go there and check for your product to clarify -
"You can check the product page of the drive on our website and see if it comes pre-formatted for Windows OS or Mac OS X.
My guess is it's formatted in NTFS (Windows OS) and that's why it turns up as read-only on your Mac. You can easily change that by re-formatting the drive. However, keep in mind that if you have any data saved onto it, it will be erased.
If you plan to use the external only on Mac OS computers, you can simply change the file system to HFS+ and reformat the drive.
Here's a tutorial that can help you with that: http://products.wdc.com/support/kb.ashx?id=e1ZvhN
If you have Windows computers as well and would like to access (read and write to) the external from both operating systems, then you'd need to use the exFAT/FAT32 file system. Here's another tutorial that explains how to do that: http://products.wdc.com/support/kb.ashx?id=Wtbgrd
However, the latter file system has some limitations, you can check those here: http://products.wdc.com/support/kb.ashx?id=X1kN54 "
