congrats on your new toy. it's so new there's probably not too many people with one yet and that's gonna make it a bit more difficult to help resolve your problem. you might also want to post over at our sister site Toshiba Thrive Forums
good luck!
since it's a sister site, just use your same user name, etc. that way when folks from here go over there they'll know it's you. you might even see me over there someday.
Did you enable USB storage? On all devices you need to pull down the notification bar and select the notification and enable before the card will mount to your computer.