EML files

Hi I recieve e-mail attachments daily and can’t open them. The file extensions are .eml. An error pops up when I try to open these. “This file does not have a program associated with it for performing this action. Create an association in My Computer goto View then to Folder Options and create an association. Does anyone know how I create this association or the program needed? I’m using Microsoft Outlook Express and Windows 98. Any help would be appreciated!!!!