'Lost' wallpaper image file -- where is setting stored?

OK, something a bit different.

Background: Recently re-installed Vista on fresh hard disk following a drive failure.
Now: Re-configuring multiple user accounts from scratch to keep everything nice and clean.
My wife's user account wallpaper on old drive was set to an image file that we had downloaded.
Now I can't find it! (and it was important to her.)

I'm sure the image is stored on the complete hard disk backup we were able to take, but I can't remember the filename (nor, of course, where we wrote it!)
So I was hoping someone from BC would be able to point me towards a file (in the backup) which stores the wallpaper filename.
(Or a likely place for writing a wallpaper file, other than C:\windows\web\wallpapers )

Well ... You evidently already know where the default background images are stored. But a custom image that you downloaded sometime in the past could be stored almost anywhere. I would start with the Start menu, and select Documents. If you don't find it there move to the Pictures folder. If you still can't locate it, try the Search feature. It would be easier if you remembered the name or part of it but start your search with *.jpg or *.gif and you'll catch most of them. A little advance warning though, you may have quite a few images stored on the unit.

Thank you.
I expected that it would be a .jpg, but as I had tried to use the search tool to find one of the default wallpaper files (whose name and location I knew) without success, I didn't fancy my chances with an unknown file in an unknown location!

The reason for asking the question is that the backup is on a USB ext drive, in amongst about 170GB of other files -- including 3 years worth of photos! (although I do know exactly where they are) -- and a file extension search would take a very long time.

Fortunately I have now found it, by chance, while copying some other user files.

Being a firm believer in thingy's Law, if I hadn't posted this request for help I wouldn't have found it!