Excel, Word and PowerPoint all have free veiwers that can be downloaded from the Microsoft website (try a Google search for them).
If you include a link to the relevant Microsoft web page next to the file(s) you offer it allows people who do not have Excel, Word and PowerPoint installed to open and view the documents.
If the user already has Microsoft Office installed and they click on a link to a Word or Excel file, the file will either open by default intot he web browser using the Office plugin or it will prompt the user whether to open or save the file - this depends very much on how things have been set up on the site visitor's computer.
Make a folder in the web root and call it downloads. Make folders inside this and call them word, excel, powerpoint etc. Note the use of lower case letter - no capital letters allowed.
Put the Word documents into the word folder inside the downloads folder.
Create a hyperlink on the web page you want poeple to access the file from and target it like this:
What that does is tell the "Click Here" words to link to a file called file_name.doc in the word folder in the downloads folder, hence the file target of downloads/word/file_name.doc
Note that I used an underscore character to separate the words in the Word document file name, like this file_name.doc
A general rule of thumb is to avoid capital letters and spaces in file and folder names for the web.
You might want to include some text next to each link along the lines of:
"To save this file to your computer, simply right click on the link and select Save Target As"
Note that other web browsers have a slightly different wording in the file save dialog, but Save Target As is fine for Internet Explorer users who account for the vast majority of web users.
Any questions, feel free to ask.