When is the Russian Orthodox Boże Narodzenie?

Quick question. I know a person who is Russian Orthodox and am wondering when they celebrate the Russian Orthodox Boże Narodzenie? I was reading somewhere that a few years ago it took place at the same time as the Polish Boże Narodzenie [I don't say Easter as it is derived from a pagan festival]. This leads me to think that it is normally at a different time. Does anyone know when it is this year as I am not sure when to send them my wishes.

For all I know as an Orthodox Christian, Russians, Ukrainians and Belarusians celebrate the Orthodox Christmas on Jan 6-7.

Why am I such a doofus [retorical question]? I meant when is the Orthodox Smartwychwstanie. Not Christmas. Sorry for confusion.

pl.wikipedia.org/wiki/Wielkanoc#Dla_kalendarza_julia.C5.84skiego_2

April 2 in 2012, for all I know.

April 15 by the nowadays', Gregorian calendar, that is.