Is it better to read the Song of Fire and Ice books before watching the HBO series?

Yes! The Books are 1 million times better than the TV series. No comparison. And in my own opinion I would recommend reading the first Book before you start on the second, because obviously they left out a lot of stuff and it will explain some situations/characters better then you could ever get from a TV show. And I really think you would enjoy it more since you watched season one. :)