PT410x is a Linux AnthroPC steeped in open source ideology, who first appeared in strip 1105 "Robot Interlude". He refuses to be known by any name other than his serial number and even objects to the term "AnthroPC", insisting on being called a "high performance open source sentient mobile workstation".
He lectures other AnthroPCs about software freedom, but is not genuinely concerned with their welfare. He is the one who talked Pintsize into a self-modification that left him incapacitated. Having done that, he proceeded to say "If he'd been running Linux this wouldn't have happened" and suggested wiping Pintsize's hard drive.
Though insistent about "freedom", he does have an owner who has upgraded him without permission. The owner has never appeared in the comic. On Formspring, Jeph Jacques said "I think I had originally planned for Marigold to be his owner, but Momo seemed more appropriate for her".
Recently his owner tried to overclock him, apparently resulting in physical damage. He now wears a cardboard box over top of, or instead of, his head.
PT410x (or a robot that looks remarkably like him) was seen leaving the group therapy session hosted by Winslow along with the other robots. His head appears to be back to normal. 
"IT IS NOT A NECKBEARD IT IS A HEAT SINK!"
It has never been mentioned what Linux distro PT410X is running. His passion about software freedom calls Debian to mind, but on the other hand he doesn't insist that people say "GNU/Linux".
Dialog between PT410X and the other robots raises questions about AnthroPC free will but doesn't resolve them. It's possible that closed-source AnthroPCs are slaves to their programming, but they certainly don't act that way.