Hi George
If you ever do get the chance to hear a Hammond (Particularly the B3) live with a good player, then do so as the sound is quite awesome.
The closest emulation of a Hammond organ is by Native Instruments, and is called the B4 (Legal Reasons) VST, http://www.native-instruments.com/index.php?id=b4ii_us&ftu=975ddd233514c4b and can be used by anybody with a computer or Open Keyboard.
Enjoy

Bill