Windows 7 at least makes a small improvement in usability which is significant.
When you have file extensions shown, and you rename a file, windows 7 automatically selects the filename, but excludes the extension, and if the user STILL changes the file extension, it asks "are you sure? The file may become unusable" - no more accidental filetype changes
It's almost safe to let the average user have file extensions shown :iagree:
Of course, in the case of newbs, or persistent PEBKACS (like my parents), there's really nothing you can do to save them from themselves - and locking up the PC with limited accounts, no program installs, no unsafe attachments, no autorun, antivirus, anti-malware, browser management & etc are still required.