What kind of school are you looking for? International or local? The best place to start is with the Guide to Warsaw. It has info on the school system & international schools in Poland. You can also try connecting with expats in the area. Expat Blogs in Poland are a great place to start.

In addition, I am working on creating listings for international schools (like Australia) on our new site, Expat Quotes, but haven't gotten to Poland yet. Anyone else have experience or advice?