Java Programming

I am trying to compile a very simple java program in windows vista, I am using jdk1.6.0_15:

public class Success {
public static void main (String [] args) {
System.out.println ("hooray!");
}
}

no problem with compilation, but I keep getting the following error message when I run java Success:

Exception in thread "main" java.lang.ClassNotFoundException: Success
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged<Native Method>
at java.net.URLClassLoader.findClass<URLClassLoader.java:188>
at java.lang.ClassLoader.loadClass<ClassLoader.java:307>
at sun.misc.Launcher$AppClassLoader.loadClass<Launcher.java:301>
at java.lang.ClassLoader.loadClass<ClassLoader.java:252>
at java.lang.ClassLoader.loadClassInternal<ClassLoader.java:320>
Couldn’t find the main class: Success program will exit.

Please help!!

thanks
Thomas