this player is 16gb
the tools will add some size to the files. but the allocated space in the hidden partition is 89MB the files are about 50 thereabouts (mine is modded)
use the tag file -on the root - to see your hidden parttion.
just know you should backup these files before you do anything.
right now i have bumblebee running through the yard (transformers 2) as a startup screen. changed the dull white batt charging and the usb connection . i use a 4 gb macro sd as backup but its not for the player as it can't read the card ,but that is what i use as storage between computers.
love the player and as for the cd its supposed to have a firmware on it. i didn't get one just want to get to it and see what in there.
makd511
gave the links already.
for animation get a gif editor to strip gif to jpegs then have fun replacing the files. the size of the original welome screen was like 20kbs i replaced them with 210 kb pics and it looks good.