Thanks for your response OPC, but I tried solving this problem using the "install over it" and the "just add more stuff" concepts and they don't work.

You cannot just install over an existing instance of BIDS. If you install BIDS from the Express Edition and then try to reinstall it from some other edition you will fail, because the other edition will detect that BIDS is already installed and it won't let you install over it.

Like you I had the idea that the installers all install the same things and all I'd need is enough add-pns (or "templates" as you call them) and suddenly the Express version of BIDS would start working. My theory was that BIDS was not working because the "Integration Services" shared component was not installed (it's not an installation option from the Express version). So my first effort was to take the Standard Edition and install Integration Services as an additional shared component. I was really surprised when this approach did not work, i.e. when BIDS popped up the same error message as it did without Integration Services.

So today it finally occurred to me that there is really something inherently wrong with the version of BIDS that ships with Express Edition, i.e. that you cannot make it work no matter how much other stuff from other editions you add. So I uninstalled both BIDS along with the Integration Services I had recently added and then reinstalled both using my described procedure. I don't claim to understand it, but basically the wording of the error message that the Express version of BIDS was delivering on its failure turned out to be true: BIDS installed from any other than the listed edition simply won't work.

So why does Express Edition install a version of BIDS that does not work no matter what you add to it, and which requires removal and replacement? I dunno. I also don't know why people buy life insurance policies for their dependent children, but I'm not gonna lose any sleep over it.