Thanks Mickey for telling me the name but it didn't ring my memory, I think it was called something else. But still, it was in the DOS days and the space will be doubled.
Continuum, it is not the files that I had compressed but the drive or partition itself, just like what Mkruer explained. This drive or partition will only be good for storage because we cannot run any programs in this compressed drive. I think this is good for backups that eat up a lot of space.
Brian, I think you are right with the performance problem. My hard disk slowed down when I compressed that partition.