I'm not familiar with the Windows Backup. I use 3rd party backup programs. The ones I use will let you back up your entire partition as an image backup. But, if you want to dig a file out of the backup image, you can mount the image as a drive letter. Then just go into Explorer, navigate down to the folder with the file, and drag it onto a regular drive. When you're done getting what you want, you unmount the image. Very convenient. I just copy files I want to back up in the ordinary way, but I also know I have another copy of the files in the backup image for the partition the file was on.
I'm using Easus ToDo backup on Windows7 and on my Vista PC I'm using Macrium Reflect. They will both let you mount an image file as a drive. I don't know if the Windows Seven backup utility has this feature or not. Quick search didn't show it to me.