I rebuilt a studio computer for my husband. He was using Cakewalk HS 2002.  How do I convert his work projects to Music Creator 6?...If a can not, what program do I need?

you should be able to open all cwp, cwb and bun files in MC6.  have you tried and it's not working?  are you getting an error?

Yeah Like Beagle said... just load the old work projects from 2002 into the new computer and use MC6 to open them and then save them to a working folder on the MC6 machine. 

Everything with cake (most everything) is forwards and backwards compatible. That has been my experience..... even opening projects from CWP8 in MC.... 

Music Creator says ""The file you have chosen differs in name from the original.  Then it brings over the "wrk" file in pieces that have no recordings in the tracks.

Did you change the hard drive, too?
The audio is usually in a different folder than the project, so if the audio is still on the old HD, it can't be imported just by opening the .wrk file.
If you didn't change the HD, you may have to search for the audio.

If you installed a new hard drive (main C drive) and the files are on the old C drive, you should be able to install the old C drive as a slave and read the files on it.

I was able to do that a few years back.... 

If not.... if the C drive is still the same one.... the files should be on the drive.... you may have to search and import them one by one to the new MC6 project.  MC6 gives the option to keep all files together in the same folders per project. 

I had to do a search one time when I deleted (intentional but later needed them) some vocal tracks. I had to go to the audio folder where they are kept even when deleted from the project.... and drag them back in and then place them correctly in the tracks. If there are numerous takes in each track with a small clip for each.... that can be a major rebuild endeavor to undertake.  In many cases it is easier to record the track again rather than to piece it back together from dozens of small clips that require exact placement.