The partitions may already be mounted. If that is the case, you only need to find out where. How they get mounted is listed in the file /etc/fstab.
Here is part of my fstab file:
/dev/hda12 / ext3 defaults 1 1
/dev/hda1 /boot ext3 defaults 1 2
/dev/hda10 /home ext3 defaults 1 2
/dev/hda11 /tmp ext3 defaults 1 2
/dev/hda9 /usr ext3 defaults 1 2
/dev/hda7 /var ext3 defaults 1 2
/dev/hda5 swap swap defaults 0 0
The first partition is /dev/hda1 and it is mounted at /boot. I can browse to /boot and see what is in it.
The other partitions are all extended partition, so the next partition is /dev/hda5. It is a swap partition, which I can't browse.
Your /etc/fstab should tell you where they are mounted. If they are not mounted, you can go to the Mandrake Control Center, select Mount Points, then Diskdrake. From this program you can add mount points for your windows partitions. Keep in mind that NTFS partitions are read only ( if you are using Windows 2000 or XP ). The windows partitions are probable mounted below the /mnt directory, with names like /mnt/win_c, /mnt/win_d, etc.
Read the output of man mount
if you want to learn more about mounting various file system types.