Assuming you have considered the usual copyright problems, goto File > Save As, and select "Web page, complete" in the "Save As type" option.
This should download all elements of any particular web page and create a folder where the elements are saved. You may have to right click the excel file and select "Save target as", and save it in the same folder. However if the link in the web page to the excel file is to another folder on the server, that may not work.
(For Firefox the options are File > Save Page As, Web page complete).
What would be the best program for downloading and saving an entire website into disk for offline browsing. I want it to look identical to the online version including links to files. For instance. If the page links to an excel file when I am offline I want to be able to click the link and view that file. Does anyone have any suggestions?