If you want to develop a windows gui app, there is little reason not to use vb over java, java has little place on the desktop right now. I say that as someone who absolutely loves programming in java.
However, everyone saying that java will soon be gone, or that there is no reason at all for it couldn't be furthur from the truth. Java is becoming the language of choice for the enterprise with J2EE, businesses are willing to sacrifice some performance if it means they wont be tied into one machine architecture for the next 20 years. Cell phones are another great example of java done right, if you are going to program any mobile app/game, chances are it'll be in j2me. Don't completely dismiss java based only on the desktop gui side of things, it will never be able to offer what native languages do.