What to do: Java vs .Net

Hey All, I currently work as a HTML Coder and I know some lower level languages (HTML, Javascript)as well as some programs (Flash, Photoshop) and was wondering what was the best thing to learn next, Java or VB.Net ( I was teaching myself VB, but I don’t want to if it’s going to be replaced.)
I do have a computer science degree, but never concentrated on a specific langugage.
Thanks