I'm to trying to upgrade Particle Explorer, Particle Editor or Inner Tube 1.01 to 2 (with the free 1.x to 2 upgrade download) but the upgrader does not find version 1.x and says I must first install version 1 to its original directory

You must have your version 1 product installed to C:\Program Files\your product. The upgrader currently has difficulty upgrading from the very first release (v 1.01), so if you have not upgraded your product to 1.02 or greater in the past you need to download update_1.bmp (right click -> save target as...) and place it in your product directory (e.g. "C:\Program Files\Particle Explorer\update_1.bmp") for the upgrade to "find" your version 1 product.