There doesn't seem to exist any converter for Windows available that can be used to convert old Claris documents (.cwk) to older Microsoft Word format (.doc). Your best bet is to access these .cwk files on some old Mac and save them to some common format like TXT and RTF, which you can then transfer to Microsoft Word and save as doc.
A utility called icWord may also be used on Macs and should allow for direct conversion of cwk to doc.