Depending what file extension the attachment is your Windows needs an application associated with that file type.

For example a .pps file needs Microsoft's PowerPoint. There is a free PowerPoint viewer available here;
http://www.microsoft.com/downloads/en/details.aspx?FamilyID=048dc840-14e1-467d-8dca-19d2a8fd7485&displaylang=en&pf=true

However if you already have Microsoft Office installed and it includes PowerPoint, then try this. Save the attachment to your hard disk, then run it from there.

All attachments need the proper application. We can't tell you which ones because we don't know what attachments you get.

But I hope that helps.

Mark