Run the old lotus app in a DOSBox DVM, and export the file in ASCII
delimited format.
If it already in ASCII form, you can import it directly. I am pretty
sure there are some free apps in Linux that will open them as well.
You would burn a Linux Live distro disk (Ubuntu Live DVD), boot that,
and then run the compatible app within that session, open the old file,
and export it as an ASCII delimited file. Office will open ASCII
delimited files or import them into a workbook.