I recommend that you don't go for books. SEOMoz.com and SEOBook.com are the two best seo resources out there. They both have free servies and pay services and you cannot go wrong should you chose to invest in either even for a short time.
Also checkout seo.alltop.com for staying up to date on the latest happenings in the SEO world. Finally if you have specific questions feel free to send me a PM I have been an active full time SEO since 1999.