Graphics viewers in Outlook 2000

My company utilizes MS Outlook 2000 for email. I and many of my co-workers can view graphics (gifs, jpgs, etc.) when they are embedded in a html-formatted message. However, when graphics files are sent -as attachments- we are unable to view them within Outlook. We must save them to disk and open them with external viewers e.g. Lview, MS Paint, etc. Since they render within an html message, internal viers must be there somewhere.
__How do I enable them?__
Thanks!