You can choose to disable backup by going to the backup settings and saving the "plan" with the selection for your OC showing Turn on backup for this PC as not checked.
On the other hand, backup is part of OneCare to help you in not losing data that you may be interested in keeping if and when your computer experiences a crash that causes data to be lost.
You should probably consider using CDR discs and not CDRW discs as OneCare does not care for erasing discs for re-use. A spindle of 50 CDR discs would cost less than $20 at Fry's. You will not re-use the discs. The first backup will take 2 to 3 discs, per the default plan, based on what you report OneCare says. You can reduce this by reviewing the "What" part of the backup plan for the PC. However, each subsequent backup will take less space as only new and changed files will be added to the backup set. You will be prompted for new discs as needed.
You can purchase and external hard drive for under $100 that plugs into a USB port. Using that as the backup destination allows you to fully automate the backup process for "When." If you use CD, you will need to be at the PC to perform the backup when OneCare prompts you. You control the schedule in the backup settings. You can backup as often as you wish - at this point *anything* is more than you ever have backed up before, so I'd probably suggest that you stick with CD and you set it to backup up every month. OneCare will prompt you that backup needs to be done.
If you click on Help in OneCare, and type Backup in the more topics search box, you will find many topics for more detailed reading on how to configure backup.
-steve
