Finally wrestled things into place inside Navi enough that I could close her up and put her back where she belongs. I don't really want to think about what she looks like inside now, and I kinda half-expect to find her shut down in the morning due to excess heat, but if not, hey. (I had to lay the new hard drives side-by-side, where one is touching the edge of the motherboard and the other's a centimeter or so from the front fans. The power connectors are actually under the main drive. It's really quite awful, but it all fits somehow; the only bad thing is that I couldn't get one of the hard drive mounting screws back in, because a cable was in the way. Ah well.)
Getting everything to fit took maybe forty-five minutes. That and lifting the CPU (with three hard drives and a CD drive!) and monitor into place has left me so tired I don't even think I have the energy to [censored].