Yes, Catholics
are Christians. There are differences obviously in what we believe, both in terms of theology and interpretation, but the core tenents as the expressed in the Nicene Creed, remain foundational. (see the link
http://www.sacred-texts.com/chr/nicene.htm if you don't know what this is).
I do think that regardless of whether or not you ultimately agree with Catholic thinking, it is something worth learning about (as is the study of religions in general). Anyways, I'm sure CDLViking could give you a better rundown on the specific issues.