I've been using Spreadsheet::ParseExcel with OpenOffice on my Linux box with great results. In Open/StarOffice, save the spreadsheet as Excel, then fire up Spreadsheet::ParseExcel and have fun. The version of Excel that you save as doesn't seem to matter, be it Excel5, 95, or 97/2000/xp unless you have cells that have > ~ 254 characters of text, in which case saving it as Excel5 will truncate the contents of those cells.

When I started doing this I was rather amused to be writing Excel spreadsheets on a Linux box using perl to be read/edited using OpenOffice with the results being read using perl-- the only thing Microsoft was the format. That said, it would be nice to have a Spreadsheet::ParseOpenOffice and Spreadsheet::WriteOpenOffice module...