Viewing video attachments

I'm having trouble viewing attachments to emails that are videos. I have a friend that likes to send funny videos, like commercials from other countries, etc. They are usually .mpg or .wmv files. The problem started when I installed my ATI new video card. The files used to open with Windows Media Player. Now, I think, they are trying to open with ATI's file player, but it doesn't work. I get a message saying, "This file does not have a program associated with it for performing this action. Create an association in the Folder Options Control panel. "
I don't know what this means nor how to do it. Any suggestions will, as usual, be appreciated.

 

Thanks for solving my question. Worked like a charm!