You can format the internal harddisk on an SL-C3200 to ext3. This has the advantage that you can then install applications on it and fully use it as a Linux harddrive.
After you've formatted it as ext3, in order to enable the Zaurus to automount it on boot, you must do the following.
| # mount -o remount,rw / |
| # mount -o remount,ro / |
The Zaurus will now mount the hdd3 automatically upon boot and you can install programs to it etc.