Convert DOC to WPS

Your first step should be using Microsoft Word, as it should still support older Microsoft Works documents, and enable you to save them in other formats. Formatting data may not be saved properly, as this feature is exclusive to newer versions of Microsoft Word. Other than that, you shouldn't be having any issues converting these documents.

Should you be using a Microsoft Word version older than 2003, make sure you install a special plugin called Microsoft Works 6-9 File Converter. 

Open source word processors, such as OpenOffice.org or LibreOffice Writer will open .wps files, yet will not let you export your documents in .wps format.