If your browser is unable to download an Excel or Doc file properly:
For Internet Explorer: On the top menu, select Tools/Internet Options/Advanced. Be sure that there are checks in the boxes for "Enable Install on Demand (Explorer)" and "Enable Install on Demand (Other)." Click OK and then try the download again.
For Mozilla Firefox and for Flock: On the top menu, select Tools/Options/Download. Then click on the View/Edit Actions button. In the search box, click on the extension of the file type (XLS for Excel, DOC for Microsoft Word, etc.) and ensure that the correct program file is listed. If not, reset to the correct program. Click Close, click OK and then try the download again.
For Opera: Opera is the most convenient browser to set for this operation. When you click on the file to download, it should immediately offer you a choice as to "Open" or "Save." I recommend saving to disk in a convenient location, but if you want to open the file without saving, Opera tells you the file it plans to use for opening the file and gives you a change button to accept an alternative.