Since you have your foot in the door already you are ahead of the game as far as employment goes. The experience is crucial these days. That being said, a degree is a requirement in most places when you start looking at better jobs. Even if you are already working for the company, they may pass you over for promotions because someone else has the same experience, but has a degree. I wish I had gotten certs while getting my degree, but that's water under the bridge now. I got an associates in 2004 and am starting work toward my CCNA now. The classes that teach you how to pass the tests may get you certified, but I don't think they really teach what you need to know. I would pass on those type of classes and instead get into a program that gets you a degree.
I got a book from Sybex which has practice tests and labs, but what really helps is having actual Cisco equipment to work with. Luckily my job has replaced all of our network hardware and I can take the old stuff and practice with it. If your company gets new equipment, see if they will let you have an old router and switch. Labs and books are nice, but really being inside the device is the best.