Sorry, but the statistics suggest that Poland, Czech Republic, and Slovakia are toast without massive immigration. I was surprised to find Poland had the lowest level of births, of the three, and with a falling trend.
2005-2010 (projected) fertility rate:
Poland: 1.23 (down from 1.25 in 2000-2005)
Czech Republic: 1.24 (up from 1.18)
Slovakia: 1.25 (up from 1.22)
source:
http://en.wikipedia.org/wiki/List_of_countries_and_territories_by_fertility_rate
I've read many mentions in the UK press of Polish immigrants for jobs in those countries. Presumably they are the reproductive age, as well. Maybe that's a factor. Sad for the host country, so valiant in its struggle of the last century to throw off communism.