Even if you aren't quite ready to Leave The Nest, if you happen to "exchange" files with other people on alternative OSes, you can help your own email client be more friendly.

One thing you can do is turn off RTF in Outlook, so that "WINMAIL.DAT" files won't be sent to user's of non-Windows systems.

To do this, go to Tools, Options, then select the Mail Format tab, specify Plain Text (or HTML) instead of Rich Text in the Send In This Message Format list, and click on OK.

If you are a Windows network administrator, on the other hand, you could use the following article to ensure that Exchange doesn't send the WINMAIL.DAT file to internet recipients.

http://support.microsoft.com/kb/q138053/ 

Enjoy!