That's a dead link, Fender62.
A winmail.dat file doesn't, in itself, normally convey any usable data (such as a document). it simply holds formatting information for another attachment which was sent with the same email. If there was another attachment with the email,. and you've managed to open it without any problems, you can ignore the winmail.dat file.
However it seems that the original attachment can sometimes be sent within the winmail.dat file. If that's happened in your case, you can use this free online service to access the original attachment:
http://www.winmaildat.com/
Chris