nice tip, in recent events of damn hackers its good to back up your files.
Backing up doesn't stop hackers.
In fact, it might make it easier.
The instructions at the beginning, if your machine is infected, and someone gets that new wallet file, you are screwed anyway, even if you delete it, if they grab it and save it.
More reason why unencrypted wallet files are just awful. More and more people will create trojans to look for that file, steal them, then be on their way with your money.
thats why you make a new wallet which only exists on the computer for about 2 minutes, or the new wallet on a virgin computer. if the hackers have your main wallet but didnt steal yet, then heres your chance right?