It's important that you back your work up.
You don't want a computer or software crash to undo all the hard work you've put in.
Upfront here are a few simple rules about backups:
1. The backup needs to be on a different machine to the original. If the backup is in the same place as the original, it's not really a backup, just a copy and it's likely if you lose one you will lose both. Backups should be spatially from the original.
2. Backups need to contain the complete file set. If the backup is only of a part of the file's you've used to build your creation then you won't be able to put your creation back together again should disaster strike.
Ok, so that out of the way, here's all the stuff you need to back up in order to keep your photobooks safe:
1. Your album itself - located in: C:\mpr500_albums\ or C:\RapidStudio_Albums\
2. The software - located in: C:\RapidStudio\MPR500 Pro 5\ or C:\RapidStudio\Program Files\MPR500 Pro 5\
3. It's quite wise to keep the original file you used to install the software. This will make reinstalling much easier.
In order to keep your albums safe whilst working on them, I would suggest you create a copy before working on a big album. This means that if something goes wrong (lets say a power failure) while saving the album, you'll still have a duplicate copy to work off of. These duplicates can be deleted whenever you feel you have a good safe copy on hand.
I hope this helps keep your albums and design elements safe.
It's always wise to make an extra backup before updating your software.