Both computers would have a "desktop" folder if they are running Windows. The more confusing thing is why the username is "bobby"
Bobby is the name that was used as the main user name when the laptop was first set up.
When you get a new computer, when you first turn it on, one of the things it asks you to do is put in your name or company name, and the other users of the computer. So, you could have a set up like this:
Admin (all computers automatically have an admin file)
Ewbie doo (User 1)
Monkie doo (user 2)
and so on.
So, it would be safe to assume that "bobby" is the original owner of the computer. Most people with computers that are "in the know" will wipe their harddrive before selling it, to ensure no personal information is left, however a lot of people will not think about it, and keep it.
It stands to reason that she got the computer from Bobby. I think someone mentioned a while back in the 400 pages her tattoo artist was named bobby?
Could have bought it from him.
When I was a computer "newb" I sold my computer and the main user name was my real name, so in the documents and settings folder, there was a folder with my name.
I doubt it's anything big imo.