I strongly caution against resizing or modifying NTFS partitions in Knoppix. The commercial Partition MAgic program can do it, but even it suggests that you should have a good backup of your data before trying to do so. So I would suggest making such a backup and, if you don't have Partition Magic (I'm guessing you don't or you would not have asked this), just deleting the partitions and recreating them fresh at the sizes you want.