you didn't quite get the picture.
As linuxcool says, the extended partition is like a folder that holds logical partitions; it's a bookkeeping mechanism for the partition table. You only need to mount the logical partitions and primary partitions to access all your data.
To answer your question, yes, my hda6, a second windows 98 partition, is mounted on /mnt/win_d, as Mandrake set it up when I installed Mandrake 8 after Windows existed.
Here is my /etc/fstab:
/dev/hda5 / reiserfs notail 1 1
none /dev/pts devpts mode=0620 0 0
/dev/hda7 /home reiserfs defaults 1 2
/dev/hdb1 /mnt/7.2 ext2 defaults,noauto 1 2
/dev/hdb6 /mnt/7.2home ext2 defaults,noauto 1 2
/dev/hdb7 /mnt/7.2usr ext2 defaults,noauto 1 2
/dev/cdrom /mnt/cdrom iso9660 ro,nosuid,noauto,exec,user,nodev 0 0
/dev/cdrom2 /mnt/cdrom2 iso9660 ro,nosuid,noauto,exec,user,nodev 0 0
/dev/fd0 /mnt/floppy vfat sync,nosuid,noauto,user,nodev,unhide 0 0
/dev/hda1 /mnt/win_c vfat user,exec,umask=0,codepage=850,iocharset=iso8859-1 0 0
/dev/hda6 /mnt/win_d vfat user,exec,umask=0,codepage=850,iocharset=iso8859-1 0 0
none /proc proc defaults 0 0
/dev/hda8 /usr reiserfs defaults 1 2
/dev/hda3 swap swap defaults 0 0
/dev/hdb5 swap swap defaults 0 0
What I did, when I wanted to add entries, was to copy the form of the other entries that were already in there. See also man fstab, man mount, man *
If you go to editting fstab, be careful, as doing it wrong can make it not boot. Take a look at this other thread where I went into it a little: