Posted 20 July 2009 - 09:35 PM
With the "Windows Complete PC Backup" feature, supposedly it is supposed to create an image of your hard drive, and all the data on it, pictures, music, programs, registry, and malware included. I don't have much experience with it (I prefer the old "ctrl-c and ctrl-v your files every weekend method, since you can actually make sure your stuff actually got backed up, but that's just me), but that's what I could find from Microsoft's article. As with the rest of Windows' backup feature, it just takes the files you specify, puts them in a compressed file in a location of your choice, and adds new files and updates changed files on a schedule.
As for number of backups, the best system to use is to get an external hard drive that you can back up every weekend and put on a shelf or in a safe, and to have another offsite or online backup, which you can get by either getting another external drive and dropping off at work, swapping with the one you keep at home every week. You can also take the online option with a service like Carbonite or Mozy, which is kept on multiple servers around the world (or so they say), which would provide redundancy if flood/tornado/earthquake/nuclear armageddon/zombies happen to take out both your at home backup and the backup at your work (or friends place/mom's house/favorite tree, etc etc etc...), however unless you have an incredibly fast upload speed, it wouldn't be the best option for backing up your giant 2TB drive, but rather for important documents, pictures, stuff you really don't want to lose. You can even do both the offsite and online backups if you please.
As for the backup files being significantly larger than your actual files, it can be summed up by the phrase "WTFIDK?". It could possibly be shadow copies of your files, or maybe you're also backing up a complete PC backup image, and don't know it.