Backed up files won't open


#1

I have backed up my pc (xp) to my My Book.  When I go to another pc (Vista), the WD program is loaded and backed up files are recognized in Explore BUT I cannot open them.  I tried an unzip program but that wouldn’t open them either.  Some have a .cat file name.

Also, the files are only numbered.  How do I know what they are (especially since many will not open). 

Thanks for your help!