I guess I am missing something here - why would you be trying to explain file extensions to them in the first place? Would they be reading the file extension, or looking at the file icon to tell them what the file is?
Although I respect your opinion, I believe that it's just the other way around. Majority of people now what an .avi file is when they see it as an extension, also is true for .mp3 -- http://kernelreloaded.blog385.com/ linux, blog, anime, spirituality, windsurf, wireless registered as user #367004 with the Linux Counter, http://counter.li.org. ICQ: 2125241 Skype: valent.turkovic