This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
It's not neccessary that a Visual Basic DLL is going to be a COM object. If the Visual basic DLL is a COM object, then you can use JACOB or other Java-COM bridges to call the DLL. If it's not, then you will have to develop your own C++ JNI layer that will wrap the Visual basic DLL and export the functions to Java