Dual Booting Class?

Linux can write to NTFS, but it's ability is limited. Essentially, you can only modify what's already there.

Also, if you're gonna dual-boot Windows with Linux make sure you install Windows first since it'll install its own bootloader no matter what. After that you can install GRUB at the same time as Linux.

Jam it back in, in the dark.

Well, first you're going to have to reformat the 120 NTFS partition to make room for the Linux partition since you can't install Linux on NTFS. Then you're going to have to figure out just how you want to do this. For the simplest setup:
/boot 50MB ext2
swap RAMx2 swap
/ Whatever's Left reiserfs (or any working filesystem)

Or you can go with a more complicated setup that can, supposedly, yield benefits. Take my setup for example (but keep in mind that I need a lot of space on /usr for Gentoo's package system and I'm using way more than 20GB):

Device      Mount Point    Size   FSType
/dev/hda1   /              1GB    ext3
/dev/hda5   /boot          50MB   ext2
/dev/hda6   /usr           20GB   reiserfs
/dev/hda7   /var           20GB   reiserfs
/dev/hda8   /opt           10GB   reiserfs
/dev/hda9   /tmp           10GB   reiserfs
/dev/hda10  /home          40GB   reiserfs

My hard drive is 200GB and in addition to these partitions I've got four NTFS partitions set aside for Windows XP.

There's nowhere I can't reach.

Congratulations. Now you can start reading all the man pages.

This thing is sticky, and I don't like it. I don't appreciate it.

Not that I'm aware of. Open up a terminal and type man.

I am a dolphin, do you want me on your body?