Giving that you already have an interest in and some background for Cisco, why not pursue their Cisco Qualified Specialist Security certification? As you climb the ladder to CCNP (and perhaps even to CCIE), knowledge of Cisco security tools, technologies and solutions will stand you in good stead. See http://www.cisco.com/warp/public/10/wwtraining/certprog/ (click on the pyramid labeled "Cisco Qualified Specialist" for more information).
In addition, I'd recommend a good general security cert like the TICSA or CISSP, plus some more operationally inclined security certification like the SANS GIAC or one of the protocol analysis credentials with a security focus. Put all those pieces together and you've got an unbeatable (and high-paying) combination of credentials.
Good luck in your pursuit of further certification.
For more information on this topic, visit these other SearchSecurity resources:
Careers and Certification Tip: A survey of vendor-specific security certifications
Careers and Certification Tip: Revisiting the vendor-neutral security certification landscape -- Again!
Best Web Links: Infosec training, careers and events
This was first published in June 2002