I have two PowerMac G4s. One is Blue and grey/white and the other has a mirrored door. You will need a usb mouse and a monitor. Both seem to be single cores from looking at the inside of the tower. I do Open Source/Free software design and these two would be and are good for animating, audio, and other artistic expressions. There are two operating systems similar to what you already know. I am making an assumption from what your husband has told me. I am able to set each with a Debian/Linux system and a FreeBSD system. The first already has packages -software - available for it. The second system needs to have packages built. I can take the tower which has the least amount of CPU and other parts for compiling. Of course, I will ask the community if they would aid and assist us in this endeavor.
We are setting up an animation station for children and will need some packages to be built. The architecture is PowerPC 32. The packages would be: GIMP, Blender, Pencil - which needs to be updated to Pencil-2d for the download area of the Pencil application in /ports/graphics - librecad, ChipmunkPhysics, the nlove animation engines, synfig & synfig studio, adgali, py27-hypatia, solarus, g2, grx, libart, openrm, pencil -see the above note, radius engine, biggles, geg, and grace
for the two dimensional animations.