If you expect to be owed a refund in March, then you don't need to worry about under-withholding in 2014. In that case, you could sell in January and keep your tax on the transaction as a sort of interest-free loan from the government through April 2015.
If you're in the 15% tax bracket, and the gains are long-term, you might also just not have to worry about taxes in either year. In that case, you'd be mildly better off selling this month because there's almost no chance of tax law changing on you.
Those are a couple of ways this could go. YMMV.