Honestly, 90% of the “hacking” books and resources out there are junk. While they may give you insight into how script kiddies work, most don’t go much further than that.
The only true way to understand computer security is to understand systems (software and/or hardware in some cases) very thoroughly. In wholly understanding a given system, you will also be able to identify its weak points and vulnerabilities.
Other good resources are:
National Vulnerability Database
http://www.softwaresecuritysolutions.com/
The Open Source Vulnerability Database
OWASP
Having said all that, it’s been quite some time since I invested any time into security-related matters, so there may be other resources that I’m not aware of.