To share data between your Mac OS X and Windows partitions:
When you’re using Windows, you can open and view files on the Mac OS X partition. To modify a
file, copy it to your Windows partition.
If you can’t see your Mac OS X partition when you’re using Windows, update Boot Camp.
Upgrading Boot Camp
When you’re using Mac OS X, you can view and open files on your Windows partition. If the
Windows partition uses the MS-DOS (FAT) format, you also can modify files on your Windows
partition. Otherwise, copy a file to your Mac OS X partition to modify it.
To see the format for your Windows partition, select it in the Finder, choose File > Get Info, click
the disclosure triangle next to General, and look at the Format field.
You can format an external disk so you can use it with both Mac OS X and Windows. For more
information, open Disk Utility (in the Utilities folder in the Applications folder) and search for
“formatting a disk for Windows.