What do I study to switch careers to IT?

I realize this is a wide open question, but not having any contact with IT professionals, I could use some guidance as to what I absolutly must know to get a good job in IT. I prefer to actually create code but I am open to networking, security… etc.

In short…

What certificates should I have
What degree if any
What specific knowledge is needed (I.E. C#, XML etc.)