To know which version is running on your system(On windows), you need to type in the command line as,

jview -versions.

I have only tried this on Windows machines with a Sun JVM installed. I'm not sure what it will do on a machine with only the Microsoft JVM or with no JVMs at all. On a machine with both the Microsoft JVM and a Sun JVM, this command returns information about the Sun JVM.  

I have only tried this on Windows machines with a Sun JVM installed. I'm not sure what it will do on a machine with only the Microsoft JVM or with no JVMs at all. On a machine with both the Microsoft JVM and a Sun JVM, this command returns information about the Sun JVM.