On whichever topic this has migrated to, 4WD on ice is no better than anything else. We see the evidence here everytime it freezes up. Us poor 2WD'ers just trudge along, and the 4WD'ers are backwards in the ditch because they not only thought they could go faster. they thought the had to.
Like Will said, it'* great in snow or mud, or something that'll give you some sort of traction, but on ice, it'* all about the rubber, not what'* pushing it.