I agree with Alec, all the best security people come from networking! That said, a CISSP will certainly open doors for you that might not be open from your other certs, especially if you are looking in a new direction, rather than a company you already work for. That said, make sure getting the cert isn't the only thing you're doing. Engage here to keep up with the news, and use some of the myriad of security sites around to keep current beyond the CBK. That way, when you are interviewing, or just talking to prospects, you have a good grasp of the state of the industry, and can be confident about it, which says a lot more than the pretty certificate on the wall. (Though I must say, ISC2 makes some pretty certificates!)
