XP or wallpaper? And.. uhm, so?
First of, as mentioned in the article itself, this screenshot proves nothing. For all we know it could simply be a background and nothing more. Not an uncommon thing to do. When I picked up Vista I really liked one of the standard backgrounds, when I moved to Win7 the default (blue/white) gave me headaches so I got the previous yellow/green Vista background back. So if you guys spotted that you'd conclude that I'd still run Vista? ;)
But even if this is so... Although XP support has been EOL'ed for consumers this doesn't include commercial licenses. Several companies can still rely on XP updates, after paying a certain fee of course. So yeah; even if he was using XP then this doesn't automatically mean that he's using an outdated and thus totally insecure environment. .... for now.