This is what i get from that:

mount: /dev/hda5 already mounted or /mnt/hda5 busy
mount: according to mtab, /dev/hda5 is already mounted on /mnt/hda5

So it is already mounted.

This is what in that partition: System Volume Information, configs.tbz, knoppix.img and knoppix.sh. What are these files? They all belong to Linux? So all this while I had the partition available to me but didn't know it. Is it possible to read Linux files from Windows?