well, u should mount them, knoppix does it automaticaly. Ofcourse if your hdd is ntfs, u won't be able to write in it without special parameters. that all i know... if your hdd is partitioned with fat just:
1) make directory where u will mount "mkdir /path/directory_name"
2) mount your windows partition:
a) in console u can see all your partiotions with "fdisk -l"
b) then u mount the partition u need (for fat32) "mount -t vfat /hda/hda* /path/directory_u_created"
* means the number of partition. it can be not only hda, also can be hdb or hdc, it depends how it's connected [primary master or slave, secondary master or slave].