The miscreant made it into only one physical computer. Not this one; I've physically disconnected the other for now, pending greater security. He (am I being sexist?) installed a couple well-known viruses and perhaps other treats. Tonight, a local hardware guy and I will go over it in detail to fix everything.
I feel like I should have done all this during summer, before the god of security went back to Indiana! Irony: When convenient, the god of security purposefully lets anyone and everyone get live image feeds of his desktop right on the web. Also, his personal superbenevolence illustrates that we can be concerned with network security while still maintaining a positive worldview!