I’ve never been happier to be wrong. Turns out you can install Movable Type on a commercial hosted Windows account. It just depends on the host. The big hang-up on Windows is the storage mechanism. Most Windows machines with Perl installed do not have the DB_File module which MT needs to store its stuff. (Well, it needs one of four modules, but the other three are not like to ever be found on Windows.)
But, sure enough, Half Price Hosting has a Perl distribution on their machines that includes DB_File. My church has a functioning MT installation to prove it. I’m thrilled.