You can configure backup to only select the file types that are important to you. See this post - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=1698096&SiteID=2 - for how to remove your old backup files and start over. OneCare adds to the first backup with all new or changed files each time you run backup and never cleans up older backups. That's a pretty big oversight in the backup component, in my opinion, and one that I hope is addressed in a future version.