Boy! Do I have an interesting answer for you. I recently put together a survey of networking certifications for another TechTarget.com Website, SearchNetworking.com. It’s called the Networking Certfication Guide and will surely tell you more than you wanted to know. Given your current background and interests, I’d suggest the relevant Microsoft certifications listed there first and foremost, primarily in the MCTS and MCITP categories.
I hope this helps to answer your question. If not, please post to this thread again, and I’ll reply to more specific questions gladly and speedily!
Thanks for posting,