[ame=http://www.youtube.com/watch?v=-pnpg00FWJY]YouTube - How does Google determine domain age, and is it important for ranking?[/ame]

After hearing what he said, be aware that aged domains can have backlinks already present out there in cyberspace that can immediately give your website relevance. If given a choice I would go for aged domains or recently expired. Just make sure it wasnt a spam site or blacklisted in its past life.