Polish, Czech, Slav... similarities?

Good evening.

Purely as a hobby, i've decided that i'd like to pick up a European language (I already speak a couple Asian languages).
I initially wanted to learn Czech, but i was comparing populations that speak languages in Europe and found that Polish outnumbers it and that it also has a lot in common with slavic languages.

tl;dr:  Anyone who speaks Polish or Czech, or any combination of those Slav languages, are there similarities?  'ppreciate your comments.

>>76
its true. every time Slobedan's popularity dips he starts a war. as a Croat i can say I've ever met any Serbs that liked the old bastard or approved of an of the wars. We Balkans people would rather get drunk and play soccer than start wars =D

>>73
sounds more like accents than dialects. Like the differences between all the British accents maybe.