When does one stop calling it a new year?

I had this conversation with someone the other day. They wished me a happy new year, even though we were several days into the new year, the question was posed, "when do we stop saying "new year"?" My best response was, "when we stop writing 2009 on things." For me, that usually takes a good 3 weeks into the new year. I caught myself just yesterday writing 09 on a check and had to cross it out, so I guess that means it's still a new year for me. We also just finished our last bit of Christmas. Sunday I took down the rest of the lights on the eves of the house and last night we got together with Bob and Sharon for dinner and gift exchange. I guess that officially closes out 2009, except for when I write it on a check. When that isn't my natural inclination, then 2010 is no longer a new year.