There also isn't as much of the "If this is executable, let's run it and *then* ask the user whether he *wants* it to run." philosophy. And things which are executable, but don't *look* executable, such as ".scr" (screensaver) files. And, based on some virus e-mails which I have received, also you can have something with an extension for something like an image (e.g. ".jpg", which actually is a ".exe" file (as determined by the "magic numbers" embedded, and apparently, the e-mail program does not pay attention to the extension and pass it to the proper program, but instead tries to execute it, depending on the system to pass it to the proper program -- thus cheerfully running the virus for you. :-) (Yes, I have seen these, but I don't use Windows to read e-mail -- or do much of anything else. :-)
Enjoy, DoN.