I still think you may have your wires crossed here.

WinRAR may have nothing to do with these files in their current state, it will open up ISO files and that's why it opens the .000 file and nothing else (000 is the first bit of the ISO).

I'm sure that if it really was a split RAR file then WinRAR would either deal with it or error out on opening it. Not only that, the default naming scheme for WinRAR is *.part000.rar, *.part001.rar etc now. Prior to that is was rar, r00,r01 etc. Would you really have forced it to use 000? I would guess 'no'.

If you have a hex editor, open the 000 file. The first few bytes will say 'Rar' in ASCII if it's a rar file. If not, it's probably a split ISO. This would fall in line with what I originally said about CloneCD. When it reads discs it splits them in chunks and names them *.000, *.001 etc.