Thanks for that! I was banging my head against the wall a bit for this one, and wondered if <Sharp Intake of Breath> Perl itself was the problem, or if it was me! Glad to know it's an Windows problem.
Rudif's tip also works - thanks: interesting to see the comment that cmd isn't a "real shell": I'm trying to write this filter, and other utilities, to make working in cmd a bit more bearable.