Hi, I will be going Beijing from 14 to 20 March 2010 with two kids, aged 2 and 8 and two adults above 50. Understand that it is still the winter season and temperature could be from -2 to 11 degree. Apart from sweater and jacket, what other things should I pack?

Do I need to bring winter jackets, scarf etc meant for winter season in case the temperature falls below zero degree? Wouldn't want to be caught by surprise, especially since I come from a tropical country. Thanks for your advice.