Getting TExaS help system running on Vista
The link for the update from Microsoft's website so that TExaS help system works on Vista is shown below.

Open it in Internet Explorer ONLY; also choose:
Windows6.0-KB917607-x86.msu version for 32 bit Vista and
Windows6.0-KB917607-x64.msu for 64 bit Vista
Install it and the help system for TExaS or any other program designed for earlier versions of Windows OS would work fine on Vista.