This t420 is a juggernaut of a laptop, its age does show and very clearly at that, If you are to buy it I can put any os you ask on it just obviously nothing too new or anything of mac os, but I can put windows 10, windows 7, windows vista (If you roll with that), I could put xp but that would be a little janky, and I can most definitely add Linux, It currently has mint Linux installed on the system. It gets hot so don't expect it to run too well on lots of workloads but its the perfect retro laptop or more cybersecurity based workstation.