If the iPod is for you, I would go with the refurb no questions.
I've purchased refurbished iPods (30 GB, Nanos, and a shuffles), iPhones (earlier this year) and a plethora of Macs (iBook G4s, iMacs, PowerBooks, 6 MacBooks, etc.) and I've never had any problems. The box is not the original but who cares if the machines are perfect and have better return policies?
My ex once bought a new MacBook and the screen failed 2 hours after purchase.
Refurb all the way.