Batch conversion

Running Microsoft Office 2007 on a Windows 7 SP-1 platform, I have a question regarding batch conversion of a file type.   I have around one thousand files in Works 2000 Word Processor format, file extension = .wps.   These files are distributed in dozens, or hundreds of folders.  I would like to convert these documents to .docx files, or even better, create copies of them with .docx extension and retain the original files.   I can convert a single .wps file by opening it in Word 2007 and saving it a s a Word document.  Is there a way to accomplish this en masse, without having to convert each file individually?   The conversion seems to require the Microsoft Office text converter.  If I simply rename the file extension of a .wps file to .docx, it can't be opened in Word due to "corruption."   I can also change the default program for .wps files to Microsoft Word.  But this doesn't save a copy of the .wps file in .docx format, unless each file is opened individually and then saved individually.