You're welcome, Mike. I am going to ask the OneCare team to advise why some 1.6 clients are not yet updated. I know that some 1.5 clients still exist due to a problem on the PC where it is installed and the only way to resolve that would be with a reinstall.
I guess one other thought at this point is that the 2.0 upgrade is pretty much a full install, so reinstalling isn't much worse than the upgrade except that you need to initiate the install after the reinstall and need to activate and reconfigure OneCare after the reinstall.
-steve