I just found this...
If I format a Hitachi Global Storage Technologies Microdrive using my PC, can I still use the Microdrive with my digital camera?
For best results, we recommend that you format the Hitachi Microdrive using the device that you will be using the most. Most devices will format the Microdrive using that FAT16 file system. 4GB and higher Microdrives require the FAT32 file system to be able to use the full capacity of the drive. Some digital cameras are not able to support FAT32. Check with the device manufacturer for any firmware updates that may be available.
I accidentally formatted my 4GB or higher Hitachi Microdrive in my camera and now it is only being detected as 2GB. How do I get my drive back to the full capacity?
If for any reason your drive is no longer being seen at the correct capacity, you have two options:
If you are using a Windows 2000 or Windows XP system, you can contact the Technical Support Center to obtain a utility that will reformat the drive to the correct capacity. The utility must be run from within Windows XP or 2000 and only while the drive is connected via card reader or PC Card adapter.
2. Connect your drive (via card reader) to a Windows 98 system and run Fdisk on the drive. You will need to delete the current partition and then recreate a partition using the entire capacity of the drive. After you created the new partition, you can then format the drive and begin using the drive again.