The other esteemed Monks have given you great answers. But I thought that you might like an alternative: There's a great package on CPAN Spreadsheet::WriteExcel that will give you the ability to do a great job in creating spreadsheets in Perl. The example code provided gives you a great starting point.

I've used that module for several jobs, and always found it to be nice. You can score plenty of points by giving your users a nicely-formatted custom spreadsheet for them. Just something to consider if the .CSV file converter you have doesn't give you enough control over the process....

--roboticus