are you rooted?
if you are not rooted then you do not have this ability to move apps to SD. we have talked about this before in other threads so you are welcome to search this specific subforum on the xoom to read up on it.
i will not go into specifics since its been discussed but to if you need general copying and deleting of data on your EXTERNAL card, you can connect the xoom up to the computer to do this, or you can remove the card and connect it to a computer, or you can use one of two apps in the market: SDCARDX and file manager HD. both allow you to move, delete, copy files to and from the card. read up on them in the market.