Well, like I said, the PowerBook has a dead circuit board; its individual components are still functional, but it will never run again unless I drop $1,200 on a new logic board, which is not going to happen.

In the case of the WinMe machine, the logic board is still fine, but the C drive finally failed, and many of the inner components of the system are close to being worn out.

I cannot explain your cats' mysterious preference for a Windows monitor over a Mac one. Perhaps they are trying to subtly shift you over to the Mac by shedding in the Windows monitor to kill it?