Change default path ?

I am trying to integrate WordPress into an existing website. The structure is as follows:
Home http://www.notreal.com
CSS http://www.notreal.com/css
Images http://www.notreal.com/images
Wordpress http://www.notreal.com/blog

the names has been changed to protect the uninformed 🙂

My site pages are php and have an ‘include header.php’ and others which are in the home directory as well. The header.php has a link to my css (<link href=”css/stylesheet.css”…>) & an image (<img src=”images/picture.jpg” …>).

In my WordPress header.php, I have “include (‘../header.php’);” (the one from the website home directory). The images do not load & there is no styling. The path to the image is “http://www.notreal.com/blog/images/picture.jpg”.

Is it possible to change the path where WordPress is looking? I don’t want to recode my existing files or change my directory layout.