Don't think about opening the excel file in the server side.
I'm not going to say that is impossible to control the client, because there are many security holes, but I'm going to say that is not easy, and is not secure (maybe you find that your code doesn't work tomorrow)
Try instaling this modules in the server (if you use ActivePerl, is very easy with ppm)

Spreadsheet-ParseExcel
Spreadsheet-ParseExcel_XLHTML
Spreadsheet-ParseExcel-Simple
Spreadsheet-WriteExcel
Spreadsheet-WriteExcel-FromDB
Spreadsheet-WriteExcel-Simple
[download]

I have used Spreadsheet-ParseExcel and is easy to make what you want.
With the first three, you can parse xls archives.
With the last three, you can write xls archives (and then you can send them to the browser)

Hopes

$_=$,=q,\,@4O,,s,^$,$\,,s,s,^,b9,s,
$_^=q,$\^-]!,,print
[download]