Word reader:
http://www.microsoft.com/downloads/details.aspx?familyid=95E24C87-8732-48D5-8689-AB826E7B8FDF&displaylang=en
Adobe Reader (for pdf files):
http://www.adobe.com/products/acrobat/readstep2.html
PowerPoint viewer:
http://www.microsoft.com/downloads/details.aspx?FamilyID=428d5727-43ab-4f24-90b7-a94784af71a4&displaylang=en