Adding blog to CMS site built with WordPress

I’ve built a small cms site for a client with WordPress and now they want to add a blog. I’m wondering the best way I should do this. Should I install another copy of wordpress e.g: mysitie.com/blog or should i do it in the original site and use a static front page like this:http://codex.wordpress.org/Creating_a_Static_Front_Page. The clients main concern is SEO, thinking that if they have a blog it will help them get found by search engines.