The most important use of this program is to restore your system to a working state if something goes wrong. If you have hard reset, everything I set up for you in the main memory of the iPAQ itself will be lost (data on the memory cards and the iPAQ File Store is safe). And if you have any other problem and can't find another way to fix it, doing a hard reset and then restoring the system from a backup will fix anything short of physical damage. Rather than having to manually reinstall the dictionary program and set it up to use the dictionaries and then make important settings changes in obscure parts of the OS yourself, you can simply use the backup file I supplied with your iPAQ to do it all automatically.
From the Start/スタート menu, tap Programs/プログラム and then iPAQ Backup. Here's what you'll see when the program starts up (well, the dates of the previous backup will be different):
It's pretty self-explanatory. The most recent backup will automatically be selected for the restore function--if that's what you want (or if you haven't created your own backup at all, so that mine is the most recent) simply tap Restore Now and your system will automatically be restored to the state it was in when that backup was made. If you've made your own backups since getting the iPAQ and you want to restore to an earlier backup or to my backup of the iPAQ's original state, you'll have to choose that backup through the options window. Restore will be followed by a mandatory soft reset (all programs restarted but no loss of data).
And speaking of making your own backups, it might be a good idea to do so. Ideally, you should be saving all documents and most data to the memory card, not the main memory, so that stuff will be safe from a crash (and because keeping as much free space as possible in the main memory is good for your system). Appointments in the Calendar, Tasks, Contacts, and Notes will be backed up automatically to your regular computer if you've set up ActiveSync or other sync software to do that, so that stuff isn't at risk. Also, any software you install from a Windows computer using ActiveSync (or WMDC on Vista) will automatically be backed up to your computer and can be restored easily the next time you connect (though it's a bit quicker and easier to reinstall them through the restore program than through ActiveSync). But if you make bigger changes to the state of your iPAQ, such as installing new software programs, and you're not using ActiveSync, you may want to make your own backup file. Thus if you later hard reset and need to restore, your can restore that program, too.