Possible Duplicate:
Windows Updates Folders (With Strange Names) in C drive
On my external hard drive "Western Digital My Book Mirror Edition 2TB USB 2.0 (WDH2U20000N)", there are lots of seemingly empty folders with seemingly random names like 7fa79879f4ca74651aa06dad5cf7fb33. What are those? Can I delete them?
More than likely your WD drive has the most free space available, and it's being recognized as a HDD (vs. a removable deivce). Because of this, Windows Updates is using that drive as a cache, and that's what those folders are.
You are safe to delete them.
I would guess that the are temp folder which are commonly created during software updates. If they are empty you should be able to delete them safely. You could move them into a subfolder and wait a day or two and see if moving them broke anything, if you want to be cautious.
