It all depends on how far you want to get with the language and why you are studying it, but i can recommend First Year Polish by Swan without hesitation. There is also Beginning Polish by Schenker, which has fantastic coverage of the sound system of Polish. However Schenker is a bit tougher in regard to his grammar explanatons, unlike Swan.
Swan's text is available on the University of Pittsburg site, as I'm sure you saw. I've seen both that and the older print [i.e. Second edition].
There are others, but I'll start here.