Once you know Cisco, how hard would it be to work on Juniper Network equipment?

Piece of cake - but that's from what I hear. I've not used Juniper. If

Any comments on the new CCDE certification? Especially compared with CCIE?

Cool -- way cool -- too cool. I spent some time with the "practical" demo (don't call it a lab), and I think they're getting it right. The testing environment appears to have included enough controls to make scoring objective, while allowing for the inherent subjectivity of design. They still have some execution to finish, but I was in a room at Networkers with a lot of old folks like me, and the old 10-year-plus CCIE crowd was generally very impressed.

I am a little confused when distinguishing between the Networking Academy, or taking an independent approach to the CCNA. I am new to the networking field and want to make sure I'm pointed the right way.

The Networking Academy has four semesters of course material, and finishing that, you should have learned the materials covered on CCNA. When you wrote in your earlier question that you had "only covered CCNA 1 and 2" not 3 and 4, I thought you were taking the Academy courses. If not, CCNA requires either one CCNA 640-802 exam, or two exams (ICND1 (640-822 and ICND2 640-816). You can self study to take the exams, take classes, etc. If you want a class, Cisco has "authorized" curriculum and partners. For self study, go to www.ciscopress.com, and click on CCNA self-study resources.

Besides Cisco certs, what other networking or security certs would you recommend?

Well, I tend to live in the Cisco world, so take this with a grain of salt. I think that the SNIA storage certs tend to have some good pull these days, and maybe CWNP wireless certs. It certainly seems that SSCP has a pretty good rep.

What's the best way to obtain a CCNP after CCNA?

I think CCNP has opportunities for saving $$ by self study and prudently taking a course or two. If your job makes you spend time on routers, or switches, or security, etc, you can pick an exam or two that's probably quicker to pass by reading/practicing rather than taking a course. For the topics for which you get little hands-on at work, take the courses. If you do well with immersion - I think that works better in general for younger folks - a bootcamp can get you a long way in a week. But in the end, "best" probably depends on your skill set coming in and your current job.

How should I prepare for a certification? Where should I start?

The best place to start, in my opinion, is to go to www.cisco.com/learnnetspace. That's a learning community from Cisco, covering CCNA, CCNP, and others. It has lots of introductory material, study aids, advice, and a place to ask questions. I'd spend a few hours just poking around there. Once you start to get your head around what the particular cert's about, then you can start looking for resources - study guides, lab gear, videos, etc.