I just loaded the page in FF3 on Linux and each section did already have its own unique link styles.
To do this in general though, give the containing element of each section an id in your HTML. Then in CSS, use decendant selectors to target the elements withing the id. For example, if your header has an id of "header" and your footer has an id of "footer", you can style links differently in each section using "#header a" and "#footer a".
Also, I noticed you're using an XHTML doctype. In that case, all your CSS rules should be written in lowercase.