I havent personally been skiing in Poland myself but a lot of the Polish people i met when in Krakow said that they tend to go to Zakopane about 100km away from Krakow. There is other activity sports there aswell i think. You can get a train from Krakow to there, it takes around 2 hours i think not 100% on that.
Zakopane is the place to go i have booked for march as this is the low season all the kids have gone back after thier winter break and the days are longer we got a log cabin for 5 nights €120 you can flight to kracow fron shannon and yes its 2 hours on the bus