AUGH I CAN'T GET NFSROOT WORKING AHHH.
On the upside, I can get Ubuntu installed on Sarah's old HP a1520n, despite it showing a black screen on boot. The magic? Hit F6 on the CD boot menu, select "nomodeset", and remove "quiet splash" from the boot options. Apparently the GeForce 6150LE doesn't get along usplash nor nouveau KMS.
Oh, and then after the install, set those GRUB options, and make them permanent by updating the line in /etc/default/grub