I'm not making any progress with accessing IBO Help.
I decided to at least move all of the above over to C:\ and now have the folder C:\IBO Help with all of the above installed there.
I HAVE the winhlp32.exe installed and can access my D7 help ok.
However, when I click on any of the IBO related help files I'm getting an error that seems to be primarily focused on intranet issues, which I'm not, unless Win7 x64/sp1 with broadband access is implicitly an 'intranet':
"Cannot display this help file. Try opening the help file again, and if you still get this message, copy the help file to a different drive, and try again."
that error is only addressed to the following issue, at least on that kb page:
"
By default, you cannot use WinHlp32.exe to access .hlp files that are stored on intranet sites. If you try to open a remote file, you will receive the following error message: <as above>"
...which doesn't appear to apply to my case, and when I look at the Group Policy KBs on that, they only mention older server versions of Windows.
And giving the IBO related help files more permissions doesn't change the error.
One anomaly that comes to mind is that when I downloaded the winhlp32.exe, it wouldn't install: it kept complaining that it wasn't the version for my system, which is the 64-bit. So, I tried the 32-bit and the same error message.
Then I tried allowing the install direct from the download and it installed ok, and I went on to access my D7 help.