Originally Posted by Teknologic
You should have all your storage freed after a factory restore. I recommend diskusage for looking through your files and folders by size.
Not true. I do wipe data/factory reset all the time to flash custom ROMs and all the data is not wiped, only the /data. Things like my music, pictures, videos all stay put in their own directories.
You should probably use adb/fastboot to reflash the factoriy image after reformatting the sdcard. Or you could just relock the device and do another OEM unlock, which does it, I believe.
Used to be a link somewhere for unrooting, relocking and going back to stock. I'll look around.