Disable USB storage but allow wireless USB to work

We are working on a solution to disable USB storage devices but we have many users that use USB wireless thumb drives. These drives contain storage so when you disable storage the cards no longer work. The majority of our cards are Sprint cards. We have tried GPO’s and local policies and we can disable the storage but every answer for this also disables the Sprint cards. Has anyone else had this issue? Any suggestions?

Some additional data — we run XP/SP2