I had this same need earlier today and found this: http://www.mediafire.com/?j081h8d0z8ij1tm It's the second book in epub and a couple of other formats. I found it by googling
clash of kings epub

I'm sure you could also find the first book by googling
game of thrones epub
You should definitely read the first book first, if you haven't. The TV series skips a lot of detail.