Have you wondered why companies change formats of files? For example, when Microsoft Office 2007 came along with it's open XML format, why would people want to switch? I know lot of people don't switch, they are still saving files in XLS format and not bothering to change them to the new version. A case can be made, however, to convert all older format files to the newer format.

There are several reasons, apart from the open XML format being accessible from any third party application, one of the major benefits we are seeing is the amount of disk space this format saves.

Yes, compared to XLS file format that the old Excel used, XLSX format can save you around 50% of total storage capacity per file. This is huge, this in itself can make a case for everyone to be upgraded to Excel 2007 (and that's just one component of Office 2007.) Financial institutions are at this point scrambling to convert their old XLS files to XLSX format, not only to save on storage costs but also to be able to tap into XLSX files from third party applications to automate processes and enhance change logging/management.

Another benefit is, XLSX files are XML files which are easily accessible/readable by third party applications. the old XLS format was proprietary and not easily accessible. This means 10 years from now, you may have trouble finding an application that can read XLS format, but you will still be able to read XLSX files.

So if you already have all your users using Office 2007, you can enjoy considerable cost savings by saving files in XLSX format as opposed to XLS. Convert the old XLS files to XLSX, this is true even for files in archive.