The registry is infested with it.
The only difference from MSXML4 I could see is that the subkeys "HELP" aren't pointing anywhere (the ones for MSXML4 point to the system32 directory).
An unrelated question...
If I use the HFEXPERT\CODECS method for MSXML4 and replace msxml4.dll (4.20.9818.0) with the version from the KB887606 hotfix (4.20.9828.0), do I still need the two CAT files that come with the hotfix or would that only be necessary in the event Microsoft ever add MSXML4 onto the Windows Update site?