looks like it might be one of the imitation Vista themes for XP. you should be able to find them pretty easily by googling it although microsoft isn't too fond of people making themes that look like their new OS.
they made one guy stop distributing his theme that imitated Vista:
<a href="http://arstechnica.com/journals/microsoft.ars/2005/12/14/2105">http://arstechnica.com/journals/microsoft.ars/2005/12/14/2105</a>