One of the best ways to protect your iBank data is to back it up regularly. iBank makes it very easy to backup your data to a .Mac account. If you do not have a .Mac account, we highly recommend getting one! You can learn more about it on Apple's website.
First, make sure you are connected to the Internet. Open the iBank data file that you want to backup (if it is not already open) and choose File>Backup to .Mac. iBank will automatically connect to your iDisk using the account information specified in the .Mac pane of System Preferences. If iBank has a problem connecting to .Mac during the backup process, check your configuration settings there.
During the backup, iBank saves a compressed copy of your data file to the following location: iDisk/Documents/iBank Backup/. The current date and the ".zip" extension will be appended to its file name (e.g. "iBank data 1-2-07.ibank.zip").
Choose iBank>Preferences and click the General button. Check "Backup to .Mac when opening an iBank document."
Every time you launch iBank or open a data file, iBank will automatically backup the file to your iDisk as described above.
In the Finder, connect to your iDisk by choosing Go>iDisk>My iDisk, then navigate to this folder: iDisk/Documents/iBank Backups/. Choose the file you want to restore, then drag and drop it from your iDisk to your Desktop (or whatever location you prefer to keep the data file in). Double-click the file to decompress it, then double-click the resulting ".ibank" file to open it with iBank.
If iBank doesn't recognize the file after decompression, rename the file so that it ends with the ".ibank" extension.
The next time you launch iBank, it will automatically remember the location of your data file and open it at startup.