Under Settings > Storage this is what I get.
Internal storage
Total space - 7.88gb
Applications - 500mb
Available - 7.39gb
SD card (I added a 32gb card)
Total space - 29.71gb
Available - 22.96gb
Tablet storage
Total space - 19.81gb
Downloads 7.44mb
Pictures, Videos - 31.12mb
Audio - 32.00kb
Misc. - 6.82gb
Available - 18.96gb
Under USB storage it says "Unavailable" so I'm not sure what that's for.
Also, when I inserted my 32gb sd card I went to applications and moved all of the apps but one to the SD card that could be moved. It seems to use the internal memory as the SD card for apps. When I go to Astro, there is an ext_sd location which is the SD card I inserted. At the root I also saw listed sdcard and sdcard2. "sdcard" included ext_sd, "sdcard2" took me right to the external card.
Whatever is going on, I should have enough storage for whatever I'd do with this thing but it would be nice to understand it better.