These are the steps that must be done in order to ensure proper downloading of Excel files to your computer.
At this point, we need to tell Netscape what type of files are to be recognized as Excel files. To do this we need to do two things.
If you have an entry that looks like this,

That's it. You're all set to download Excel files. If not, then you should repeat the steps over again.
Note: If Excel is already open when you select a new file to download, the file will save to the desktop and the Save/Open window will appear. Just click on the newly downloaded file and it will open in Excel.