FYI, after some research I found that the version I had, 500e200beta.zip, (the last and latest version), does work in Windows 7 x64. The trick is to right click the .exe and change it to Windows XP SP3 Compatible, then run the install. I got it working and got my MX-500 reprogrammed. I hope to be able to keep using it for a long time. I have one new unused MX-500 still, available if this one ever up and dies.