How can you convert PRN files to PDF?

A .prn file is about the most useless file type Microsoft have come up with. Windows programmes allow you to 'print to a file' but then give you no way of actually doing anything with the file. If your printer was a PostScript type, then it might be possible to convert the .prn file to a .pdf by renaming it as .ps instead of .prn and running it though a programme such as ghostscript.