Java plugin doesn't work with Internet Explorer for 7u1 b01.
And 2 checkboxes in Java control panel can't be set on:
  1. Advanced->Default Java for browsers->Microsoft Internet Explorer
   ( actually not editable in Vista family, but expected to be checked
     if IE available )
  2. Advanced->Java Plug-in->Enable the next generation Java Plug-in
If you make these checkboxes checked, on the next run of Javaq CPL they become unchecked again.
Plugin works OK:
    for 7u1 b01    + Mozilla Firefox
    for 7 fcs b147 + IE
See comments for details.